Infundibulocystic basal cell carcinoma: a newly described variant.

A report by Tozawa and Ackerman (Am J Dermatopathol 9(6):474, 1987) upon a distinctive type of basal cell carcinoma with a particular type of follicular differentiation has stimulated lively correspondence in the literature of dermatopathology. The lesion in question presents itself clinically as a basal cell carcinoma on the face and histopathologically as a neoplasm typified by small size, sharp circumscription, and a unique combination of kinds of follicular differentiation, namely, follicular germs and infundibula. The principal point of contention concerning this neoplasm has been whether it is truly a special variant of basal cell carcinoma or whether it is actually a trichoepithelioma. More extensive studies of this singular neoplasm, including its occurrence in patients with nevoid basal cell carcinoma syndrome, and review of the very few portrayals of it in the literature, have consolidated our view that it is indeed a special variant of basal cell carcinoma. We now present (a) new information about an early stage in the evolution of the neoplasm in point, (b) evidence to validate classification of it as a basal cell carcinoma, and (c) a critical appraisal of other lesions that might pose problems in differential diagnosis. Finally, justification is provided for the designation "infundibulocystic basal cell carcinoma."