Christian Albornoz, MD

The Diagnosis: Aneurysmal Dermatofibroma

A shave biopsy of the entire tumor was performed at the initial visit. Histologic examination with hematoxylin and eosin staining revealed a fibrohistiocytic infiltrate containing cleftlike cavernous spaces lined by epithelial cells (Figure, A). Immunohistochemical staining revealed factor XIIIa expression on fibrohistiocytic cells (Figure, B). CD34 was expressed on vascular endothelial cells, but it failed to highlight the fibrohistiocytic space (Figure, C). Overall, these findings supported the diagnosis of aneurysmal dermatofibroma. The lesion healed without complications, and the patient was counseled on the risk for recurrence. He was offered localized excision but opted for conservative management without excision and close follow-up and monitoring.

Dermatofibromas are common benign cutaneous nodules that often are asymptomatic and occur on the extremities. Dermatofibromas also are known as cutaneous fibrous histiocytomas and have numerous histologic variants. Aneurysmal dermatofibroma (also called aneurysmal fibrous histiocytoma) is a rare histologic variant of dermatofibroma presenting as a slow-growing exophytic tumor that can be purple, red, brown, or blue. Although classic dermatofibromas typically constitute a straightforward diagnosis, aneurysmal dermatofibromas often are more challenging to clinically differentiate from other cutaneous neoplasms. Additionally, due to the exophytic nature and larger size (0.5–4.0 cm), aneurysmal dermatofibromas do not exhibit the characteristic dimple (Fitzpatrick) sign found in many dermatofibromas. Aneurysmal dermatofibromas are 10 times more likely to recur than classic dermatofibromas.^1-4

Aneurysmal dermatofibromas can mimic other cutaneous neoplasms, some indolent and others more aggressive. Similar to aneurysmal dermatofibromas, solitary neurofibromas and nevi lipomatosus can appear as asymptomatic exophytic nodules with a similar spectrum of color and indolent clinical courses. In nevus lipomatosus, the dermis is almost entirely replaced by mature adipose tissue.⁵ Solitary neurofibromas represent a proliferation of neuromesenchymal cells with haphazardly arranged, wavy nuclei characteristic of nerve cells.⁶ Dermatofibrosarcoma protuberans can be distinguished from aneurysmal dermatofibroma by lack of factor XIIIa expression and diffuse positivity for CD34.⁷ Finally, aneurysmal dermatofibromas may resemble vascular tumors such as nodular Kaposi sarcoma. Kaposi sarcoma can be differentiated from an aneurysmal dermatofibroma by the presence of characteristic vascular wrapping, the absence of fibrohistiocytic cells, and expression of human herpesvirus 8 latent nuclear antigen-1.^1,8 Although aneurysmal dermatofibromas are of low malignant potential, they are associated with a higher rate of recurrence compared to common dermatofibromas.⁹ Definitive treatment involves complete excision with follow-up to ensure no signs of recurrence.¹⁰ Incomplete excision can increase the likelihood of recurrence, especially for larger aneurysmal dermatofibromas. Aneurysmal dermatofibromas are one of the subtypes of dermatofibromas that may extend into the subcutaneous tissue. Han et al² found that 77.8% of aneurysmal dermatofibromas extended into subcutaneous tissue. Recognizing the clinical and pathological features of this rare subtype of dermatofibroma can aid dermatologists in appropriate recognition and management.

The Diagnosis: Aneurysmal Dermatofibroma

A shave biopsy of the entire tumor was performed at the initial visit. Histologic examination with hematoxylin and eosin staining revealed a fibrohistiocytic infiltrate containing cleftlike cavernous spaces lined by epithelial cells (Figure, A). Immunohistochemical staining revealed factor XIIIa expression on fibrohistiocytic cells (Figure, B). CD34 was expressed on vascular endothelial cells, but it failed to highlight the fibrohistiocytic space (Figure, C). Overall, these findings supported the diagnosis of aneurysmal dermatofibroma. The lesion healed without complications, and the patient was counseled on the risk for recurrence. He was offered localized excision but opted for conservative management without excision and close follow-up and monitoring.

Dermatofibromas are common benign cutaneous nodules that often are asymptomatic and occur on the extremities. Dermatofibromas also are known as cutaneous fibrous histiocytomas and have numerous histologic variants. Aneurysmal dermatofibroma (also called aneurysmal fibrous histiocytoma) is a rare histologic variant of dermatofibroma presenting as a slow-growing exophytic tumor that can be purple, red, brown, or blue. Although classic dermatofibromas typically constitute a straightforward diagnosis, aneurysmal dermatofibromas often are more challenging to clinically differentiate from other cutaneous neoplasms. Additionally, due to the exophytic nature and larger size (0.5–4.0 cm), aneurysmal dermatofibromas do not exhibit the characteristic dimple (Fitzpatrick) sign found in many dermatofibromas. Aneurysmal dermatofibromas are 10 times more likely to recur than classic dermatofibromas.^1-4

Aneurysmal dermatofibromas can mimic other cutaneous neoplasms, some indolent and others more aggressive. Similar to aneurysmal dermatofibromas, solitary neurofibromas and nevi lipomatosus can appear as asymptomatic exophytic nodules with a similar spectrum of color and indolent clinical courses. In nevus lipomatosus, the dermis is almost entirely replaced by mature adipose tissue.⁵ Solitary neurofibromas represent a proliferation of neuromesenchymal cells with haphazardly arranged, wavy nuclei characteristic of nerve cells.⁶ Dermatofibrosarcoma protuberans can be distinguished from aneurysmal dermatofibroma by lack of factor XIIIa expression and diffuse positivity for CD34.⁷ Finally, aneurysmal dermatofibromas may resemble vascular tumors such as nodular Kaposi sarcoma. Kaposi sarcoma can be differentiated from an aneurysmal dermatofibroma by the presence of characteristic vascular wrapping, the absence of fibrohistiocytic cells, and expression of human herpesvirus 8 latent nuclear antigen-1.^1,8 Although aneurysmal dermatofibromas are of low malignant potential, they are associated with a higher rate of recurrence compared to common dermatofibromas.⁹ Definitive treatment involves complete excision with follow-up to ensure no signs of recurrence.¹⁰ Incomplete excision can increase the likelihood of recurrence, especially for larger aneurysmal dermatofibromas. Aneurysmal dermatofibromas are one of the subtypes of dermatofibromas that may extend into the subcutaneous tissue. Han et al² found that 77.8% of aneurysmal dermatofibromas extended into subcutaneous tissue. Recognizing the clinical and pathological features of this rare subtype of dermatofibroma can aid dermatologists in appropriate recognition and management.

The Diagnosis: Aneurysmal Dermatofibroma

A shave biopsy of the entire tumor was performed at the initial visit. Histologic examination with hematoxylin and eosin staining revealed a fibrohistiocytic infiltrate containing cleftlike cavernous spaces lined by epithelial cells (Figure, A). Immunohistochemical staining revealed factor XIIIa expression on fibrohistiocytic cells (Figure, B). CD34 was expressed on vascular endothelial cells, but it failed to highlight the fibrohistiocytic space (Figure, C). Overall, these findings supported the diagnosis of aneurysmal dermatofibroma. The lesion healed without complications, and the patient was counseled on the risk for recurrence. He was offered localized excision but opted for conservative management without excision and close follow-up and monitoring.

Dermatofibromas are common benign cutaneous nodules that often are asymptomatic and occur on the extremities. Dermatofibromas also are known as cutaneous fibrous histiocytomas and have numerous histologic variants. Aneurysmal dermatofibroma (also called aneurysmal fibrous histiocytoma) is a rare histologic variant of dermatofibroma presenting as a slow-growing exophytic tumor that can be purple, red, brown, or blue. Although classic dermatofibromas typically constitute a straightforward diagnosis, aneurysmal dermatofibromas often are more challenging to clinically differentiate from other cutaneous neoplasms. Additionally, due to the exophytic nature and larger size (0.5–4.0 cm), aneurysmal dermatofibromas do not exhibit the characteristic dimple (Fitzpatrick) sign found in many dermatofibromas. Aneurysmal dermatofibromas are 10 times more likely to recur than classic dermatofibromas.^1-4

Aneurysmal dermatofibromas can mimic other cutaneous neoplasms, some indolent and others more aggressive. Similar to aneurysmal dermatofibromas, solitary neurofibromas and nevi lipomatosus can appear as asymptomatic exophytic nodules with a similar spectrum of color and indolent clinical courses. In nevus lipomatosus, the dermis is almost entirely replaced by mature adipose tissue.⁵ Solitary neurofibromas represent a proliferation of neuromesenchymal cells with haphazardly arranged, wavy nuclei characteristic of nerve cells.⁶ Dermatofibrosarcoma protuberans can be distinguished from aneurysmal dermatofibroma by lack of factor XIIIa expression and diffuse positivity for CD34.⁷ Finally, aneurysmal dermatofibromas may resemble vascular tumors such as nodular Kaposi sarcoma. Kaposi sarcoma can be differentiated from an aneurysmal dermatofibroma by the presence of characteristic vascular wrapping, the absence of fibrohistiocytic cells, and expression of human herpesvirus 8 latent nuclear antigen-1.^1,8 Although aneurysmal dermatofibromas are of low malignant potential, they are associated with a higher rate of recurrence compared to common dermatofibromas.⁹ Definitive treatment involves complete excision with follow-up to ensure no signs of recurrence.¹⁰ Incomplete excision can increase the likelihood of recurrence, especially for larger aneurysmal dermatofibromas. Aneurysmal dermatofibromas are one of the subtypes of dermatofibromas that may extend into the subcutaneous tissue. Han et al² found that 77.8% of aneurysmal dermatofibromas extended into subcutaneous tissue. Recognizing the clinical and pathological features of this rare subtype of dermatofibroma can aid dermatologists in appropriate recognition and management.

The Diagnosis: Wells Syndrome 

Histopathologic examination of the biopsy demonstrated overlying acanthosis, focal spongiosis, and exocytosis. There also was proliferation and thickening of superficial capillaries and papillary fibrosis (Figure, A). There was a mixed interstitial and perivascular inflammatory infiltrate consisting of lymphocytes, histiocytes, plasma cells, and eosinophils (Figure, A and B). Occasional flame figures were identified (Figure, C). 

Wells syndrome, also known as eosinophilic cellulitis, was first described in 1971 by Wells¹ as a recurrent granulomatous dermatitis with eosinophilia. Rarely reported worldwide, this chronic relapsing condition is characterized by a pronounced eosinophilic infiltrate of the dermis resembling urticaria or cellulitis.² The exact etiology has not been elucidated; however, links to certain medications, vaccines, exaggerated arthropod reactions, infections, and malignancies have been documented.³  

Wells syndrome is a diagnosis of exclusion and lacks a predictable dermatologic presentation, thereby mandating focused clinical follow-up as well as correlation with histopathology findings. Although the classic histologic hallmark of Wells syndrome is scattered flame figures, this finding is not specific and can be found in other hypereosinophilic conditions.² Clinical manifestations most often consist of 2 distinct phases: an initial painful burning or pruritic sensation, followed by the development of erythematous and edematous dermal plaques that may heal with slight hyperpigmentation over 4 to 8 weeks. A case series of 19 patients demonstrated variants of Wells syndrome, with an annular granuloma-like appearance found primarily in adults and the signature plaque-type appearance predominating in children.⁴  

Acute urticaria is characterized by pruritic erythematous wheals secondary to a histamine-mediated response brought on by a variety of triggers, typically allergic and self-resolving within 24 hours. When such lesions last longer than 24 hours, biopsy should be performed to exclude urticarial vasculitis, which is characterized by a burning or painful sensation rather than pruritis, in addition to dermal neutrophilia and perivascular infiltrate on histology. Erythema migrans of Lyme disease begins at the site of a tick bite, evolving from a red macule to an expanding targetoid lesion and typically is not pruritic. Infectious cellulitis presents with warm, tender, and poorly defined erythematous patches; can progress rapidly; and is accompanied by systemic symptoms such as fevers, malaise, and lymphadenopathy.  

Best evidence favors the use of moderate- to high-dose corticosteroids as first-line treatment.⁵ The use of tumor necrosis factor blockers, various immunomodulating agents, and combination therapy with levocetirizine and hydroxyzine have demonstrated variable levels of efficacy, albeit often followed by high rates of relapse with drug discontinuation.⁶  

The Diagnosis: Wells Syndrome 

Histopathologic examination of the biopsy demonstrated overlying acanthosis, focal spongiosis, and exocytosis. There also was proliferation and thickening of superficial capillaries and papillary fibrosis (Figure, A). There was a mixed interstitial and perivascular inflammatory infiltrate consisting of lymphocytes, histiocytes, plasma cells, and eosinophils (Figure, A and B). Occasional flame figures were identified (Figure, C). 

Wells syndrome, also known as eosinophilic cellulitis, was first described in 1971 by Wells¹ as a recurrent granulomatous dermatitis with eosinophilia. Rarely reported worldwide, this chronic relapsing condition is characterized by a pronounced eosinophilic infiltrate of the dermis resembling urticaria or cellulitis.² The exact etiology has not been elucidated; however, links to certain medications, vaccines, exaggerated arthropod reactions, infections, and malignancies have been documented.³  

Wells syndrome is a diagnosis of exclusion and lacks a predictable dermatologic presentation, thereby mandating focused clinical follow-up as well as correlation with histopathology findings. Although the classic histologic hallmark of Wells syndrome is scattered flame figures, this finding is not specific and can be found in other hypereosinophilic conditions.² Clinical manifestations most often consist of 2 distinct phases: an initial painful burning or pruritic sensation, followed by the development of erythematous and edematous dermal plaques that may heal with slight hyperpigmentation over 4 to 8 weeks. A case series of 19 patients demonstrated variants of Wells syndrome, with an annular granuloma-like appearance found primarily in adults and the signature plaque-type appearance predominating in children.⁴  

Acute urticaria is characterized by pruritic erythematous wheals secondary to a histamine-mediated response brought on by a variety of triggers, typically allergic and self-resolving within 24 hours. When such lesions last longer than 24 hours, biopsy should be performed to exclude urticarial vasculitis, which is characterized by a burning or painful sensation rather than pruritis, in addition to dermal neutrophilia and perivascular infiltrate on histology. Erythema migrans of Lyme disease begins at the site of a tick bite, evolving from a red macule to an expanding targetoid lesion and typically is not pruritic. Infectious cellulitis presents with warm, tender, and poorly defined erythematous patches; can progress rapidly; and is accompanied by systemic symptoms such as fevers, malaise, and lymphadenopathy.  

Best evidence favors the use of moderate- to high-dose corticosteroids as first-line treatment.⁵ The use of tumor necrosis factor blockers, various immunomodulating agents, and combination therapy with levocetirizine and hydroxyzine have demonstrated variable levels of efficacy, albeit often followed by high rates of relapse with drug discontinuation.⁶  

The Diagnosis: Wells Syndrome 

Histopathologic examination of the biopsy demonstrated overlying acanthosis, focal spongiosis, and exocytosis. There also was proliferation and thickening of superficial capillaries and papillary fibrosis (Figure, A). There was a mixed interstitial and perivascular inflammatory infiltrate consisting of lymphocytes, histiocytes, plasma cells, and eosinophils (Figure, A and B). Occasional flame figures were identified (Figure, C). 

Wells syndrome, also known as eosinophilic cellulitis, was first described in 1971 by Wells¹ as a recurrent granulomatous dermatitis with eosinophilia. Rarely reported worldwide, this chronic relapsing condition is characterized by a pronounced eosinophilic infiltrate of the dermis resembling urticaria or cellulitis.² The exact etiology has not been elucidated; however, links to certain medications, vaccines, exaggerated arthropod reactions, infections, and malignancies have been documented.³  

Wells syndrome is a diagnosis of exclusion and lacks a predictable dermatologic presentation, thereby mandating focused clinical follow-up as well as correlation with histopathology findings. Although the classic histologic hallmark of Wells syndrome is scattered flame figures, this finding is not specific and can be found in other hypereosinophilic conditions.² Clinical manifestations most often consist of 2 distinct phases: an initial painful burning or pruritic sensation, followed by the development of erythematous and edematous dermal plaques that may heal with slight hyperpigmentation over 4 to 8 weeks. A case series of 19 patients demonstrated variants of Wells syndrome, with an annular granuloma-like appearance found primarily in adults and the signature plaque-type appearance predominating in children.⁴  

Acute urticaria is characterized by pruritic erythematous wheals secondary to a histamine-mediated response brought on by a variety of triggers, typically allergic and self-resolving within 24 hours. When such lesions last longer than 24 hours, biopsy should be performed to exclude urticarial vasculitis, which is characterized by a burning or painful sensation rather than pruritis, in addition to dermal neutrophilia and perivascular infiltrate on histology. Erythema migrans of Lyme disease begins at the site of a tick bite, evolving from a red macule to an expanding targetoid lesion and typically is not pruritic. Infectious cellulitis presents with warm, tender, and poorly defined erythematous patches; can progress rapidly; and is accompanied by systemic symptoms such as fevers, malaise, and lymphadenopathy.  

Best evidence favors the use of moderate- to high-dose corticosteroids as first-line treatment.⁵ The use of tumor necrosis factor blockers, various immunomodulating agents, and combination therapy with levocetirizine and hydroxyzine have demonstrated variable levels of efficacy, albeit often followed by high rates of relapse with drug discontinuation.⁶