title: Basaloid follicular hamartoma of the eyelid.
abstract: An 86-year-old woman slowly developed a solitary 0.3 3 0.2-cm papule on the left lower eyelid. Complete excision disclosed a honeycombed lesion composed of interlacing basaloid strands unattached to the epidermis but rather extending into the dermis from a dilated hair follicle. The diagnosis was a solitary basaloid follicular hamartoma that can also occur in multiple, generalized, and inherited forms, sometimes with an associated systemic disease. The lesion exhibited a distinctive CD34-positive, mildly cellular myxoid stroma with many CK20-positive Merkel cells scattered within the basaloid cellular strands, which exhibited BCL-2 positivity only within the outermost cells bordering the stroma. These immunohistochemical features are the opposite of those displayed by basal cell carcinomas, which require more aggressive surgical management. Besides basal cell carcinomas, the differential diagnosis of basaloid follicular hamartoma includes fibrofolliculoma, tumor of the follicular infundibulum, poroma, and trabecular (Merkel cell) carcinoma.
authors.affiliation: David G Cogan Laboratory of Ophthalmic Pathology, Massachusetts Eye and Ear Infirmary and Harvard Medical School, Boston, Massachusetts 02114 , USA. Fred_Jakobiec@meei.harvard.edu
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Jakobiec
authors.forename: Fouad R
authors.initials: FR
authors.lastname: Zakka
authors.forename: Nancy
authors.initials: N
authors.lastname: Kim
mesh_terms: D000369:Aged, 80 and over; D018952:Antigens, CD34 / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D005141:Eyelid Diseases / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D005260:Female; D018859:Hair Follicle / Q000002:abnormalities / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D006222:Hamartoma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D053554:Keratin-20 / Q000378:metabolism; D019394:Ki-67 Antigen / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D012873:Skin Diseases, Genetic / Q000378:metabolism / Q000473:pathology* / Q000601:surgery
chemical_list: D018952:Antigens, CD34; D014408:Biomarkers, Tumor; D053554:Keratin-20; D019394:Ki-67 Antigen; D019253:Proto-Oncogene Proteins c-bcl-2