Michael R. Migden, MD

To the Editor:

The transient and generic appearance of exercise-induced vasculitis (EIV) makes it a commonly misdiagnosed condition. The lesion often is only encountered through photographs brought by the patient or by taking a thorough history. The lack of findings on clinical inspection and the generic appearance of EIV may lead to misdiagnosis as stasis dermatitis due to its presentation as erythematous lesions on the medial lower legs.

A 68-year-old woman with no notable medical history was referred to our clinic for suspected stasis dermatitis. At presentation, no lesions were identified on the legs, but she brought photographs of an erythematous urticarial eruption on the medial lower legs, extending from just above the sock line to the mid-calves (Figure). The eruptions had occurred over the last 16 years, typically presenting suddenly after playing tennis or an extended period of walking and spontaneously resolving in 4 days. The lesions were painless, restricted to the calves, and were not pruritic, though the initial presentation 16 years prior included pruritic pigmented patches on the anterior thighs. Because the condition spontaneously improved within days, no treatment was attempted. An ultrasound venous reflux study ruled out venous reflux and stasis dermatitis.

Histologic examination demonstrates features of leukocytoclastic vasculitis with perivascular lymphocytic and neutrophilic infiltrates.² Erythrocyte extravasation, IgM deposits, and identification of C3 also have been reported.^8,9 The spontaneous resolution of EIV has led to treatment efforts being focused on preventative measures. Several cases have reported some degree of success in preventing EIV with compression therapy, venoactive drugs, systemic steroids, and application of topical steroids before exercise.³

The clinical morphology and lower leg location of EIV leads to a common misdiagnosis of stasis dermatitis. Clinical history of a transient nature is the mainstay in the diagnosis of EIV, and ultrasound venous reflux study may be required in some cases. Preventative measures are superior to treatment and mainly include compression therapy.

To the Editor:

The transient and generic appearance of exercise-induced vasculitis (EIV) makes it a commonly misdiagnosed condition. The lesion often is only encountered through photographs brought by the patient or by taking a thorough history. The lack of findings on clinical inspection and the generic appearance of EIV may lead to misdiagnosis as stasis dermatitis due to its presentation as erythematous lesions on the medial lower legs.

A 68-year-old woman with no notable medical history was referred to our clinic for suspected stasis dermatitis. At presentation, no lesions were identified on the legs, but she brought photographs of an erythematous urticarial eruption on the medial lower legs, extending from just above the sock line to the mid-calves (Figure). The eruptions had occurred over the last 16 years, typically presenting suddenly after playing tennis or an extended period of walking and spontaneously resolving in 4 days. The lesions were painless, restricted to the calves, and were not pruritic, though the initial presentation 16 years prior included pruritic pigmented patches on the anterior thighs. Because the condition spontaneously improved within days, no treatment was attempted. An ultrasound venous reflux study ruled out venous reflux and stasis dermatitis.

Histologic examination demonstrates features of leukocytoclastic vasculitis with perivascular lymphocytic and neutrophilic infiltrates.² Erythrocyte extravasation, IgM deposits, and identification of C3 also have been reported.^8,9 The spontaneous resolution of EIV has led to treatment efforts being focused on preventative measures. Several cases have reported some degree of success in preventing EIV with compression therapy, venoactive drugs, systemic steroids, and application of topical steroids before exercise.³

The clinical morphology and lower leg location of EIV leads to a common misdiagnosis of stasis dermatitis. Clinical history of a transient nature is the mainstay in the diagnosis of EIV, and ultrasound venous reflux study may be required in some cases. Preventative measures are superior to treatment and mainly include compression therapy.

To the Editor:

The transient and generic appearance of exercise-induced vasculitis (EIV) makes it a commonly misdiagnosed condition. The lesion often is only encountered through photographs brought by the patient or by taking a thorough history. The lack of findings on clinical inspection and the generic appearance of EIV may lead to misdiagnosis as stasis dermatitis due to its presentation as erythematous lesions on the medial lower legs.

A 68-year-old woman with no notable medical history was referred to our clinic for suspected stasis dermatitis. At presentation, no lesions were identified on the legs, but she brought photographs of an erythematous urticarial eruption on the medial lower legs, extending from just above the sock line to the mid-calves (Figure). The eruptions had occurred over the last 16 years, typically presenting suddenly after playing tennis or an extended period of walking and spontaneously resolving in 4 days. The lesions were painless, restricted to the calves, and were not pruritic, though the initial presentation 16 years prior included pruritic pigmented patches on the anterior thighs. Because the condition spontaneously improved within days, no treatment was attempted. An ultrasound venous reflux study ruled out venous reflux and stasis dermatitis.

Histologic examination demonstrates features of leukocytoclastic vasculitis with perivascular lymphocytic and neutrophilic infiltrates.² Erythrocyte extravasation, IgM deposits, and identification of C3 also have been reported.^8,9 The spontaneous resolution of EIV has led to treatment efforts being focused on preventative measures. Several cases have reported some degree of success in preventing EIV with compression therapy, venoactive drugs, systemic steroids, and application of topical steroids before exercise.³

The clinical morphology and lower leg location of EIV leads to a common misdiagnosis of stasis dermatitis. Clinical history of a transient nature is the mainstay in the diagnosis of EIV, and ultrasound venous reflux study may be required in some cases. Preventative measures are superior to treatment and mainly include compression therapy.

To the Editor:

A 55-year-old man with a history of Graves disease treated with radioactive iodine and Graves ophthalmopathy was referred to our dermatology clinic by his endocrinologist with a 2-year history of severe pretibial myxedema (PM) that had failed treatment with systemic immunosuppressants after diagnosis by an outside dermatologist in the United Kingdom approximately 2 years prior. In addition to burning pain and difficulty walking associated with progressive “enlarging” of the lower legs and feet (Figure, A and B), the patient reported that he consistently had to find larger shoes (size 13 at the current presentation). His medications included gabapentin for foot pain and levothyroxine for hypothyroidism.

Physical examination revealed diffuse, waxy, indurated, flesh-colored and erythematous plaques and nodules with a peau d’orange appearance on the dorsal feet, ankles, and lower legs. Laboratory evaluation revealed a thyroid stimulating immunoglobulin level of 617% (reference range, <140%) and mild anemia. His thyroid stimulating hormone and free T4 levels, a comprehensive metabolic panel, and lipid panel were all within reference range.

Treatment with oral, intravenous, and intralesional steroids; cyclosporine; and azathioprine were tried prior to presentation to our clinic with no improvement. The patient was started on pentoxifylline (400 mg 3 times daily), intralesional triamcinolone acetonide (5 mg/mL every 3–4 weeks), clobetasol propionate ointment 0.05% under occlusion twice daily, short-stretch bandages, and compression stockings (20–30 mm Hg). The baseline circumference of the extremities also were measured (right ankle, 12 in; left ankle, 11.5 in; right and left mid-plantar feet, 12 in).

At 3-week follow-up, the lesions had flattened with softening of the skin. The patient reported his legs were smaller and he had bought a new pair of shoes at size 8.5 (Figure, C). He noted less pain and difficulty with walking. The circumference of the extremities was measured again (right ankle, 10.2 in; left ankle, 10 in; right and left mid-plantar feet, 10.5 in). The patient continued treatment and was followed for 3 months. At each visit, clinical improvement was noted as well as report of decreased pain while walking (Figure, D).

Pretibial myxedema is a known manifestation of Graves disease that almost always occurs in the presence of Graves ophthalmopathy. Pretibial myxedema occurs in 0.5% to 4.3% of patients with Graves disease and variably manifests as diffuse nonpitting edema or localized, waxy, indurated plaques or nodules.^1,2

The proposed pathogenesis of PM is that autoantibodies directed against the thyroid receptors cross-react with the fibroblasts of the skin,^2,3 which stimulates the fibroblasts to produce high amounts of glycosaminoglycans, especially hyaluronic acid, in the dermis and subcutis of the pretibial area. It is not known why there is a predilection for the anterior shins, but mechanical factors and dependent position (ie, leg position is lower than the level of the heart) may be involved.⁴

The mainstay of treatment for PM is topical and intralesional corticosteroids, which may have a benefit in mild to moderate disease; however, in cases of severe disease that is refractory to intralesional and topical corticosteroids under occlusion, more aggressive treatment is required. Systemic immunosuppressants such as cyclosporine, azathioprine, and corticosteroids have proven useful in some but not all cases.^5,6

Our patient did not respond to treatment with systemic and intralesional corticosteroids, cyclosporine, or azathioprine before he presented to our clinic; however, the lesions were dramatically improved after 3 weeks of treatment with pentoxifylline, intralesional and topical corticosteroids under occlusion, short-stretch bandages, and compression stockings.

Pentoxifylline inhibits the proliferation and glycosaminoglycan synthesis of cultured fibroblasts derived from patients with Graves ophthalmology and PM.⁷ It has been shown to reduce thickness of skin lesions when used in combination with topical or intralesional steroids.^3,8 Corticosteroids are thought to block fibroblast-mediated glycosaminoglycan production.^3,9 The deposition of mucin, which is comprised of glycosaminoglycans, expands the dermal tissue and causes fluid to accumulate; it also causes compression of dermal lymphatics, worsening the dermal edema. Because fluid accumulates, the use of short-stretch bandages and compression stockings may provide additional benefit, as was seen in our patient, whose shoe size decreased from a 13 to an 8.5 within 3 weeks of treatment.

In conclusion, the combination of pentoxifylline, intralesional and topical corticosteroids under occlusion, short-stretch bandages, and compression garments can cause substantial improvement in severe PM refractory to systemic immunosuppressants.

To the Editor:

A 55-year-old man with a history of Graves disease treated with radioactive iodine and Graves ophthalmopathy was referred to our dermatology clinic by his endocrinologist with a 2-year history of severe pretibial myxedema (PM) that had failed treatment with systemic immunosuppressants after diagnosis by an outside dermatologist in the United Kingdom approximately 2 years prior. In addition to burning pain and difficulty walking associated with progressive “enlarging” of the lower legs and feet (Figure, A and B), the patient reported that he consistently had to find larger shoes (size 13 at the current presentation). His medications included gabapentin for foot pain and levothyroxine for hypothyroidism.

Physical examination revealed diffuse, waxy, indurated, flesh-colored and erythematous plaques and nodules with a peau d’orange appearance on the dorsal feet, ankles, and lower legs. Laboratory evaluation revealed a thyroid stimulating immunoglobulin level of 617% (reference range, <140%) and mild anemia. His thyroid stimulating hormone and free T4 levels, a comprehensive metabolic panel, and lipid panel were all within reference range.

Treatment with oral, intravenous, and intralesional steroids; cyclosporine; and azathioprine were tried prior to presentation to our clinic with no improvement. The patient was started on pentoxifylline (400 mg 3 times daily), intralesional triamcinolone acetonide (5 mg/mL every 3–4 weeks), clobetasol propionate ointment 0.05% under occlusion twice daily, short-stretch bandages, and compression stockings (20–30 mm Hg). The baseline circumference of the extremities also were measured (right ankle, 12 in; left ankle, 11.5 in; right and left mid-plantar feet, 12 in).

At 3-week follow-up, the lesions had flattened with softening of the skin. The patient reported his legs were smaller and he had bought a new pair of shoes at size 8.5 (Figure, C). He noted less pain and difficulty with walking. The circumference of the extremities was measured again (right ankle, 10.2 in; left ankle, 10 in; right and left mid-plantar feet, 10.5 in). The patient continued treatment and was followed for 3 months. At each visit, clinical improvement was noted as well as report of decreased pain while walking (Figure, D).

Pretibial myxedema is a known manifestation of Graves disease that almost always occurs in the presence of Graves ophthalmopathy. Pretibial myxedema occurs in 0.5% to 4.3% of patients with Graves disease and variably manifests as diffuse nonpitting edema or localized, waxy, indurated plaques or nodules.^1,2

The proposed pathogenesis of PM is that autoantibodies directed against the thyroid receptors cross-react with the fibroblasts of the skin,^2,3 which stimulates the fibroblasts to produce high amounts of glycosaminoglycans, especially hyaluronic acid, in the dermis and subcutis of the pretibial area. It is not known why there is a predilection for the anterior shins, but mechanical factors and dependent position (ie, leg position is lower than the level of the heart) may be involved.⁴

The mainstay of treatment for PM is topical and intralesional corticosteroids, which may have a benefit in mild to moderate disease; however, in cases of severe disease that is refractory to intralesional and topical corticosteroids under occlusion, more aggressive treatment is required. Systemic immunosuppressants such as cyclosporine, azathioprine, and corticosteroids have proven useful in some but not all cases.^5,6

Our patient did not respond to treatment with systemic and intralesional corticosteroids, cyclosporine, or azathioprine before he presented to our clinic; however, the lesions were dramatically improved after 3 weeks of treatment with pentoxifylline, intralesional and topical corticosteroids under occlusion, short-stretch bandages, and compression stockings.

Pentoxifylline inhibits the proliferation and glycosaminoglycan synthesis of cultured fibroblasts derived from patients with Graves ophthalmology and PM.⁷ It has been shown to reduce thickness of skin lesions when used in combination with topical or intralesional steroids.^3,8 Corticosteroids are thought to block fibroblast-mediated glycosaminoglycan production.^3,9 The deposition of mucin, which is comprised of glycosaminoglycans, expands the dermal tissue and causes fluid to accumulate; it also causes compression of dermal lymphatics, worsening the dermal edema. Because fluid accumulates, the use of short-stretch bandages and compression stockings may provide additional benefit, as was seen in our patient, whose shoe size decreased from a 13 to an 8.5 within 3 weeks of treatment.

In conclusion, the combination of pentoxifylline, intralesional and topical corticosteroids under occlusion, short-stretch bandages, and compression garments can cause substantial improvement in severe PM refractory to systemic immunosuppressants.

To the Editor:

A 55-year-old man with a history of Graves disease treated with radioactive iodine and Graves ophthalmopathy was referred to our dermatology clinic by his endocrinologist with a 2-year history of severe pretibial myxedema (PM) that had failed treatment with systemic immunosuppressants after diagnosis by an outside dermatologist in the United Kingdom approximately 2 years prior. In addition to burning pain and difficulty walking associated with progressive “enlarging” of the lower legs and feet (Figure, A and B), the patient reported that he consistently had to find larger shoes (size 13 at the current presentation). His medications included gabapentin for foot pain and levothyroxine for hypothyroidism.

Physical examination revealed diffuse, waxy, indurated, flesh-colored and erythematous plaques and nodules with a peau d’orange appearance on the dorsal feet, ankles, and lower legs. Laboratory evaluation revealed a thyroid stimulating immunoglobulin level of 617% (reference range, <140%) and mild anemia. His thyroid stimulating hormone and free T4 levels, a comprehensive metabolic panel, and lipid panel were all within reference range.

Treatment with oral, intravenous, and intralesional steroids; cyclosporine; and azathioprine were tried prior to presentation to our clinic with no improvement. The patient was started on pentoxifylline (400 mg 3 times daily), intralesional triamcinolone acetonide (5 mg/mL every 3–4 weeks), clobetasol propionate ointment 0.05% under occlusion twice daily, short-stretch bandages, and compression stockings (20–30 mm Hg). The baseline circumference of the extremities also were measured (right ankle, 12 in; left ankle, 11.5 in; right and left mid-plantar feet, 12 in).

At 3-week follow-up, the lesions had flattened with softening of the skin. The patient reported his legs were smaller and he had bought a new pair of shoes at size 8.5 (Figure, C). He noted less pain and difficulty with walking. The circumference of the extremities was measured again (right ankle, 10.2 in; left ankle, 10 in; right and left mid-plantar feet, 10.5 in). The patient continued treatment and was followed for 3 months. At each visit, clinical improvement was noted as well as report of decreased pain while walking (Figure, D).

Pretibial myxedema is a known manifestation of Graves disease that almost always occurs in the presence of Graves ophthalmopathy. Pretibial myxedema occurs in 0.5% to 4.3% of patients with Graves disease and variably manifests as diffuse nonpitting edema or localized, waxy, indurated plaques or nodules.^1,2

The proposed pathogenesis of PM is that autoantibodies directed against the thyroid receptors cross-react with the fibroblasts of the skin,^2,3 which stimulates the fibroblasts to produce high amounts of glycosaminoglycans, especially hyaluronic acid, in the dermis and subcutis of the pretibial area. It is not known why there is a predilection for the anterior shins, but mechanical factors and dependent position (ie, leg position is lower than the level of the heart) may be involved.⁴

The mainstay of treatment for PM is topical and intralesional corticosteroids, which may have a benefit in mild to moderate disease; however, in cases of severe disease that is refractory to intralesional and topical corticosteroids under occlusion, more aggressive treatment is required. Systemic immunosuppressants such as cyclosporine, azathioprine, and corticosteroids have proven useful in some but not all cases.^5,6

Our patient did not respond to treatment with systemic and intralesional corticosteroids, cyclosporine, or azathioprine before he presented to our clinic; however, the lesions were dramatically improved after 3 weeks of treatment with pentoxifylline, intralesional and topical corticosteroids under occlusion, short-stretch bandages, and compression stockings.

Pentoxifylline inhibits the proliferation and glycosaminoglycan synthesis of cultured fibroblasts derived from patients with Graves ophthalmology and PM.⁷ It has been shown to reduce thickness of skin lesions when used in combination with topical or intralesional steroids.^3,8 Corticosteroids are thought to block fibroblast-mediated glycosaminoglycan production.^3,9 The deposition of mucin, which is comprised of glycosaminoglycans, expands the dermal tissue and causes fluid to accumulate; it also causes compression of dermal lymphatics, worsening the dermal edema. Because fluid accumulates, the use of short-stretch bandages and compression stockings may provide additional benefit, as was seen in our patient, whose shoe size decreased from a 13 to an 8.5 within 3 weeks of treatment.

In conclusion, the combination of pentoxifylline, intralesional and topical corticosteroids under occlusion, short-stretch bandages, and compression garments can cause substantial improvement in severe PM refractory to systemic immunosuppressants.

Terra firma–forme dermatosis (TFFD) was first described by Duncan et al,¹ in 1987 and is characterized by brown to black pigmented plaques on the skin that cannot be removed with soap and water but are easily wiped away with isopropyl alcohol. Since that publication, relatively few case reports and case series have been published. We present a case of linear TFFD on the midline back of a 46-year-old woman.

Case Report

A 46-year-old woman presented to our clinic for evaluation of a lesion on the back that had been present for 3 years. An initial diagnosis of acanthosis nigricans or lichen simplex chronicus was made and treatment with topical triamcinolone cream 0.1% was initiated. However, after 8 months of treatment, no improvement was observed and the patient returned to our clinic. Her medical history was notable for obesity, type 2 diabetes mellitus, and hypertension. The patient stated that she maintained good hygiene, including daily to twice-daily showers with soap. Physical examination revealed a linear, hyperkeratotic, dark-brown plaque on the midline back extending from the top of the sacrum to the upper back (Figure 1). No other areas of skin involvement were noted. The hyperpigmented scales were easily removed with an isopropyl alcohol swab, which confirmed a diagnosis of TFFD (Figure 2). The patient was given ammonium lactate lotion 12% to apply to the lesion once daily using an applicator stick if the lesion recurred. She reported some improvement during this treatment. She occasionally had recurrent lesions, which were removed with isopropyl alcohol on subsequent dermatology visits.

Comment

Terra firma–forme dermatosis is an idiopathic condition that, although benign, can cause notable distress to patients. It presents clinically as asymptomatic, brown or black, hyperpigmented, hyperkeratotic, verrucous, or papillomatous plaques or light scaling in some cases.^1-4 It can be readily cleared by rubbing with isopropyl alcohol but is resistant to ordinary soap and water.¹

Recent reports have shown that TFFD may be more common than once thought.^4-6 Although commonly observed in children, TFFD has been reported over a wide range of ages (4–86 years).^2-5 The face, ankles, neck, and trunk are the most commonly affected areas.^4,7,8 Areas that are less commonly affected often include surgical incision sites as well as the scalp, axillae, back, umbilical area, pubic area, arms, and legs.^2-4,8,9 The lesions may be generalized or localized and are sometimes found to be symmetrical.^4,10,11

The exact etiology of TFFD is unknown but is believed to be due to melanin retention and alteration or a delay of keratinization that leads to the buildup and compaction of scales.^1,2,12 Poor hygiene generally is considered to exclude the diagnosis of TFFD in favor of dermatitis neglecta.^6,12,13 Histopathology typically shows epidermal acanthosis, lamellar hyperkeratosis, and orthokeratotic whorls.^3,7 However, biopsies seldom are performed due to the ease of diagnosis by removal by cleaning the lesion with isopropyl alcohol.

The diagnosis is confirmed by resolution of the rash after cleaning with isopropyl alcohol.¹ Further confirmation of this diagnosis can be achieved through dermoscopy, as large, polygonal, platelike, brown scales can be found arranged together giving a mosaic pattern.⁶ In addition to cleaning with isopropyl alcohol,^5,8 other treatments have shown efficacy for more resistant cases of TFFD, including topical keratolytic agents (eg, lactic acid, urea lotion).^4,14

Conclusion

Terra firma–forme dermatosis is a condition that if recognized early, may provide treatment satisfaction through immediate removal of the lesions. Physicians should keep TFFD in their differential during evaluation of patients with asymptomatic, hyperpigmented, hyperkeratotic plaques. Awareness of TFFD is important, as early diagnosis can prevent unnecessary treatment and diagnostic workup.

Terra firma–forme dermatosis (TFFD) was first described by Duncan et al,¹ in 1987 and is characterized by brown to black pigmented plaques on the skin that cannot be removed with soap and water but are easily wiped away with isopropyl alcohol. Since that publication, relatively few case reports and case series have been published. We present a case of linear TFFD on the midline back of a 46-year-old woman.

Case Report

A 46-year-old woman presented to our clinic for evaluation of a lesion on the back that had been present for 3 years. An initial diagnosis of acanthosis nigricans or lichen simplex chronicus was made and treatment with topical triamcinolone cream 0.1% was initiated. However, after 8 months of treatment, no improvement was observed and the patient returned to our clinic. Her medical history was notable for obesity, type 2 diabetes mellitus, and hypertension. The patient stated that she maintained good hygiene, including daily to twice-daily showers with soap. Physical examination revealed a linear, hyperkeratotic, dark-brown plaque on the midline back extending from the top of the sacrum to the upper back (Figure 1). No other areas of skin involvement were noted. The hyperpigmented scales were easily removed with an isopropyl alcohol swab, which confirmed a diagnosis of TFFD (Figure 2). The patient was given ammonium lactate lotion 12% to apply to the lesion once daily using an applicator stick if the lesion recurred. She reported some improvement during this treatment. She occasionally had recurrent lesions, which were removed with isopropyl alcohol on subsequent dermatology visits.

Comment

Terra firma–forme dermatosis is an idiopathic condition that, although benign, can cause notable distress to patients. It presents clinically as asymptomatic, brown or black, hyperpigmented, hyperkeratotic, verrucous, or papillomatous plaques or light scaling in some cases.^1-4 It can be readily cleared by rubbing with isopropyl alcohol but is resistant to ordinary soap and water.¹

Recent reports have shown that TFFD may be more common than once thought.^4-6 Although commonly observed in children, TFFD has been reported over a wide range of ages (4–86 years).^2-5 The face, ankles, neck, and trunk are the most commonly affected areas.^4,7,8 Areas that are less commonly affected often include surgical incision sites as well as the scalp, axillae, back, umbilical area, pubic area, arms, and legs.^2-4,8,9 The lesions may be generalized or localized and are sometimes found to be symmetrical.^4,10,11

The exact etiology of TFFD is unknown but is believed to be due to melanin retention and alteration or a delay of keratinization that leads to the buildup and compaction of scales.^1,2,12 Poor hygiene generally is considered to exclude the diagnosis of TFFD in favor of dermatitis neglecta.^6,12,13 Histopathology typically shows epidermal acanthosis, lamellar hyperkeratosis, and orthokeratotic whorls.^3,7 However, biopsies seldom are performed due to the ease of diagnosis by removal by cleaning the lesion with isopropyl alcohol.

The diagnosis is confirmed by resolution of the rash after cleaning with isopropyl alcohol.¹ Further confirmation of this diagnosis can be achieved through dermoscopy, as large, polygonal, platelike, brown scales can be found arranged together giving a mosaic pattern.⁶ In addition to cleaning with isopropyl alcohol,^5,8 other treatments have shown efficacy for more resistant cases of TFFD, including topical keratolytic agents (eg, lactic acid, urea lotion).^4,14

Conclusion

Terra firma–forme dermatosis is a condition that if recognized early, may provide treatment satisfaction through immediate removal of the lesions. Physicians should keep TFFD in their differential during evaluation of patients with asymptomatic, hyperpigmented, hyperkeratotic plaques. Awareness of TFFD is important, as early diagnosis can prevent unnecessary treatment and diagnostic workup.

Terra firma–forme dermatosis (TFFD) was first described by Duncan et al,¹ in 1987 and is characterized by brown to black pigmented plaques on the skin that cannot be removed with soap and water but are easily wiped away with isopropyl alcohol. Since that publication, relatively few case reports and case series have been published. We present a case of linear TFFD on the midline back of a 46-year-old woman.

Case Report

A 46-year-old woman presented to our clinic for evaluation of a lesion on the back that had been present for 3 years. An initial diagnosis of acanthosis nigricans or lichen simplex chronicus was made and treatment with topical triamcinolone cream 0.1% was initiated. However, after 8 months of treatment, no improvement was observed and the patient returned to our clinic. Her medical history was notable for obesity, type 2 diabetes mellitus, and hypertension. The patient stated that she maintained good hygiene, including daily to twice-daily showers with soap. Physical examination revealed a linear, hyperkeratotic, dark-brown plaque on the midline back extending from the top of the sacrum to the upper back (Figure 1). No other areas of skin involvement were noted. The hyperpigmented scales were easily removed with an isopropyl alcohol swab, which confirmed a diagnosis of TFFD (Figure 2). The patient was given ammonium lactate lotion 12% to apply to the lesion once daily using an applicator stick if the lesion recurred. She reported some improvement during this treatment. She occasionally had recurrent lesions, which were removed with isopropyl alcohol on subsequent dermatology visits.

Comment

Terra firma–forme dermatosis is an idiopathic condition that, although benign, can cause notable distress to patients. It presents clinically as asymptomatic, brown or black, hyperpigmented, hyperkeratotic, verrucous, or papillomatous plaques or light scaling in some cases.^1-4 It can be readily cleared by rubbing with isopropyl alcohol but is resistant to ordinary soap and water.¹

Recent reports have shown that TFFD may be more common than once thought.^4-6 Although commonly observed in children, TFFD has been reported over a wide range of ages (4–86 years).^2-5 The face, ankles, neck, and trunk are the most commonly affected areas.^4,7,8 Areas that are less commonly affected often include surgical incision sites as well as the scalp, axillae, back, umbilical area, pubic area, arms, and legs.^2-4,8,9 The lesions may be generalized or localized and are sometimes found to be symmetrical.^4,10,11

The exact etiology of TFFD is unknown but is believed to be due to melanin retention and alteration or a delay of keratinization that leads to the buildup and compaction of scales.^1,2,12 Poor hygiene generally is considered to exclude the diagnosis of TFFD in favor of dermatitis neglecta.^6,12,13 Histopathology typically shows epidermal acanthosis, lamellar hyperkeratosis, and orthokeratotic whorls.^3,7 However, biopsies seldom are performed due to the ease of diagnosis by removal by cleaning the lesion with isopropyl alcohol.

The diagnosis is confirmed by resolution of the rash after cleaning with isopropyl alcohol.¹ Further confirmation of this diagnosis can be achieved through dermoscopy, as large, polygonal, platelike, brown scales can be found arranged together giving a mosaic pattern.⁶ In addition to cleaning with isopropyl alcohol,^5,8 other treatments have shown efficacy for more resistant cases of TFFD, including topical keratolytic agents (eg, lactic acid, urea lotion).^4,14

Conclusion

Terra firma–forme dermatosis is a condition that if recognized early, may provide treatment satisfaction through immediate removal of the lesions. Physicians should keep TFFD in their differential during evaluation of patients with asymptomatic, hyperpigmented, hyperkeratotic plaques. Awareness of TFFD is important, as early diagnosis can prevent unnecessary treatment and diagnostic workup.