Structure and significance of the pits with their tumors in the nevoid basal cell carcinoma syndrome.

Parallel histopathologic, histochemical, scanning, and transmission electron microscopic (EM) observations were made on palmar pits of one patient and on palmar pits, with an unprecedented number of basal cell carcinomas. of another patient. The first scanning view of tumor growing into the lumen of a pit from the genetically defective epidermis below is presented. The anatomy of the pit is demonstrated for the first time by scanning view of a transected pit. Our observations confirmed those of Hashimoto et al on the mechanisms involved in premature desquamation of the stratum corneum and on the true nature of the epithelium at the base of the pit. This epithelium resembled closely basal cell epithelioma and represented carcinoma in situ. The striking demarcation afforded by the axure B stain of normal and abnormal portions of the palmar epidermis with pit and the poor stainability of the pit with tumor was likewise confirmed. The tumors exhibit aggressive behavior infrequently.