Routine hematoxylin-eosin–stained sections demonstrated a platelike proliferation of keratinocytes with pallid cytoplasm in an interanastomosing array within the papillary dermis. In some of the biopsy specimens, foci of germinative differentiation and outer sheath differentiation were evident.
The patient was treated with a carbon dioxide ultrapulsed laser, with complete histologic and clinical resolution of lesions in the treated sites.
Tumor of the follicular infundibulum is an uncommon, benign adnexal neoplasm, with a recently reported incidence of 10 per 100,000 cutaneous neoplasms.1 Over a 5-year period, the Dermatopathology Service at the University of California, San Francisco, diagnosed 63 cases of TFI among approximately 80,000 cutaneous biopsy specimens, so the true incidence appears to be greater. There have been several reported cases of "eruptive," or multiple, TFIs, some of which showed a clinical presentation similar to that in our case.1-7 The lesions tend to be asymptomatic and most notable after sun exposure.1 The reason for accentuation after UV exposure is not known, but we postulate that these benign lesions may have lost the ability to pigment normally and thus appear more prominently on tanned skin.
Hypopigmented Papules of the Cheeks, Neck, and Shoulders. Arch Dermatol. 1999;135(4):463–a–468. doi:10-1001/pubs.Arch Dermatol.-ISSN-0003-987x-135-4-dof0499
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