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ANSWER
The answer is temporal triangular alopecia (choice “d”), an unusual form of permanent hair loss preferentially affecting the exact area depicted in this case.
Alopecia areata (choice “a”) involves localized hair loss. By contrast, this patient never had hair in this area to lose.
Nevus sebaceous (choice “b”) is a congenital hamartoma that is typically hairless; there are no follicles, and the bumpy, rough surface is composed of sebaceous globules.
Cutis aplasia (choice “c”) manifests with hairless lesions, but there is marked aplasia of the skin as well and no surface adnexae, let alone hairs or follicles.
DISCUSSION
Temporal triangular alopecia (TTA) is an unusual type of alopecia. Of unknown origin, it usually affects this area of the scalp—and usually unilaterally. Approximately one-third of TTA patients are born with the condition; the rest develop it in the first two to three years of life. As in this case, it is often wrongly attributed to the use of forceps but has nothing to do with trauma. One school of thought holds that TTA is probably an inherited condition—but others disagree.
TTA was originally known as congenital triangular alopecia. However, when enough cases had been accumulated to accurately determine the nature of the condition, it was realized that TTA is not always congenital or triangular. Thus, a new name was bestowed.
The hallmark of TTA is the normal number of hair follicles that only grow vellus hairs. The solitary peripheral tuft of terminal dark hairs is typical of TTA and thus a confirmatory finding.
TREATMENT/PROGNOSIS
TTA is by definition permanent. Since there’s no inflammation (a key difference from alopecia areata), steroids are useless. The only successful treatment for TTA, if any is attempted, is hair transplantation. As of this writing, the family is mulling this treatment option.
ANSWER
The answer is temporal triangular alopecia (choice “d”), an unusual form of permanent hair loss preferentially affecting the exact area depicted in this case.
Alopecia areata (choice “a”) involves localized hair loss. By contrast, this patient never had hair in this area to lose.
Nevus sebaceous (choice “b”) is a congenital hamartoma that is typically hairless; there are no follicles, and the bumpy, rough surface is composed of sebaceous globules.
Cutis aplasia (choice “c”) manifests with hairless lesions, but there is marked aplasia of the skin as well and no surface adnexae, let alone hairs or follicles.
DISCUSSION
Temporal triangular alopecia (TTA) is an unusual type of alopecia. Of unknown origin, it usually affects this area of the scalp—and usually unilaterally. Approximately one-third of TTA patients are born with the condition; the rest develop it in the first two to three years of life. As in this case, it is often wrongly attributed to the use of forceps but has nothing to do with trauma. One school of thought holds that TTA is probably an inherited condition—but others disagree.
TTA was originally known as congenital triangular alopecia. However, when enough cases had been accumulated to accurately determine the nature of the condition, it was realized that TTA is not always congenital or triangular. Thus, a new name was bestowed.
The hallmark of TTA is the normal number of hair follicles that only grow vellus hairs. The solitary peripheral tuft of terminal dark hairs is typical of TTA and thus a confirmatory finding.
TREATMENT/PROGNOSIS
TTA is by definition permanent. Since there’s no inflammation (a key difference from alopecia areata), steroids are useless. The only successful treatment for TTA, if any is attempted, is hair transplantation. As of this writing, the family is mulling this treatment option.
ANSWER
The answer is temporal triangular alopecia (choice “d”), an unusual form of permanent hair loss preferentially affecting the exact area depicted in this case.
Alopecia areata (choice “a”) involves localized hair loss. By contrast, this patient never had hair in this area to lose.
Nevus sebaceous (choice “b”) is a congenital hamartoma that is typically hairless; there are no follicles, and the bumpy, rough surface is composed of sebaceous globules.
Cutis aplasia (choice “c”) manifests with hairless lesions, but there is marked aplasia of the skin as well and no surface adnexae, let alone hairs or follicles.
DISCUSSION
Temporal triangular alopecia (TTA) is an unusual type of alopecia. Of unknown origin, it usually affects this area of the scalp—and usually unilaterally. Approximately one-third of TTA patients are born with the condition; the rest develop it in the first two to three years of life. As in this case, it is often wrongly attributed to the use of forceps but has nothing to do with trauma. One school of thought holds that TTA is probably an inherited condition—but others disagree.
TTA was originally known as congenital triangular alopecia. However, when enough cases had been accumulated to accurately determine the nature of the condition, it was realized that TTA is not always congenital or triangular. Thus, a new name was bestowed.
The hallmark of TTA is the normal number of hair follicles that only grow vellus hairs. The solitary peripheral tuft of terminal dark hairs is typical of TTA and thus a confirmatory finding.
TREATMENT/PROGNOSIS
TTA is by definition permanent. Since there’s no inflammation (a key difference from alopecia areata), steroids are useless. The only successful treatment for TTA, if any is attempted, is hair transplantation. As of this writing, the family is mulling this treatment option.
Since birth, this 8-year-old boy has had a “bald spot” on his scalp. The pediatrician who attended the birth suggested trauma as the cause, since forceps were used to facilitate delivery. But the problem has failed to resolve, leaving the boy an object of ridicule among his classmates. According to the patient’s parents, there has never been any broken skin or hair growth in the area. There is no family history of similar problems, and the child’s health history is unremarkable. The child’s current pediatrician, who made the referral to dermatology, suggested the lesion might be a form of nevus sebaceous. The affected site is roughly triangular, measures about 3 cm on each side, and is located just inside the temporal scalp. The hair loss in this sharply circumscribed area is almost complete, with a lone tuft of darker terminal hairs on the inferior aspect of the site. No redness or epidermal disturbance (eg, scaling) is noted. Dermatoscopic examination (with 10x magnification) reveals a normal number of follicles and hairs. The latter are vellus hairs, except for the aforementioned solitary tuft. The rest of the scalp, including the same location on the opposite side, is free of any significant changes.
