One hundred and nine lesions from 50 patients with epithelioma adenoides cysticum of Brooke and 83 lesions from 82 patients with solitary trichoepithelioma were analyzed clinically and pathologically. The clinical picture of epithelioma adenoides cysticum may mimic adenoma sebaceum of Pringle, syringoma, or basal cell nevi. Solitary trichoepithelioma is not distinctive clinically and may be confused with intradermal nevus, basal cell carcinoma, and dermatofibroma. Solitary trichoepithelioma did not occur in patients with a family history of multiple lesions, and this finding is against the concept that solitary lesions are a forme fruste of epithelioma adenoides cysticum. Associated congenital anomalies were not found except in the one autopsied patient with epithelioma adenoides cysticum, who had multiple cysts of the lungs and kidneys.
The lesions of epithelioma adenoides cysticum and solitary trichoepithelioma show similar characteristic histopathologic changes, consisting of keratinous cysts with attempted pilar formation and islands of basaloid cells embedded in an abundant stroma. There were no histochemical differences in the solitary and multiple lesions. Solitary trichoepithelioma and epithelioma adenoides cysticum cannot be distinguished except by clinical history.
Spontaneous ulceration of lesions of both epithelioma adenoides cysticum and solitary trichoepithelioma occurred rarely, but there was no histopathologic evidence of transformation to basal cell carcinoma in any of the lesions.
Solitary trichoepithelioma and epithelioma adenoides cysticum most likely arise from a pluripotential cell. Their differentiation is directed toward hair structures. In the case of epithelioma adenoides cysticum the tumor formation is apparently a manifestation of a hereditary defect.
GRAY HR, HELWIG EB. Epithelioma Adenoides Cysticum and Solitary Trichoepithelioma. Arch Dermatol. 1963;87(1):102–114. doi:10.1001/archderm.1963.01590130108018
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