Case 1: Nodular BCC consists of large nodules of basaloid cells that bud and drop off from the overlying epidermis (or hair follicles). This nest contains a cystically dilated center, a common degenerative change.

Note the peripheral pallisading of the nests. Sometimes, cribriforming or pseudoglandular formation may arise within the nodule, a so-called adenoid cystic pattern.

Clefting/retraction artifact is characteristic.

Another image demonstrating well-demarcated nodules of tumor with pallisading around the rim of the nests.

The stroma is rich in mucins, lending a blue hue.

Nodular BCC is likely the most common form of BCC, and is characterized by nodules of basaloid cells that bud or drop off from the epidermis. When cystic spaces from in the nodules, one may refer to the pattern as nodular/nodulocystic (Crowson).

Nodular type BCC is typically a pearly pink or flesh colored papule with telangiectasia. Lesions may be translucent or slightly erythematous with a rolled border. Most arise in adulthood, with UV light exposure as a major risk factor. Other risk factors include radiation exposure, arsenic, coal tar derivatives.

Patients with xeroderma pigmentosum or Gorlin syndrome have an inherited predisposition of forming multiple BCCs. XP patients have a defect in repairing UV-induced DNA damage and patients with Gorlin syndrome (a.k.a. nevoid BCC syndrome) have an inherited defect in the PTCH (patched) gene. Of note, this mutation is also present in some 30-50% of sporadic BCCs. The clinical manifestations of nevoid BCC syndrome include the numerous (up to thousands) of BCCs. Individuals also manifest cysts of the skin and of the jaws (odontogenic keratocysts), skeletal anomalies (fused of splayed ribs), calcification of the falx cerebri, palmoplantar pits, cleft lip/palate, bilateral calcified ovarian fibromas, medulloblastomas, among others (Berg).

• Epidermis : Basal Cell Carcinoma

• Adnexal : Trichoblastoma