Two cases of discrete adenoid pseudogland formation within benign intradermal melanocytic nevi.

We report 2 cases of benign intradermal melanocytic nevi with discrete glandular elements and mucin deposition engendering a diagnostic dilemma. The preliminary differential included entrapment of adnexal structures, collision with an adnexal neoplasm such as adenoid cystic carcinoma or metastatic adenocarcinoma. A colloidal iron special stain confirmed the deposition of mucin; however, a pankeratin AE1/AE3 immunohistochemical cocktail was surprisingly negative. Closer cytological examination of the discrete "glands" combined with nearby pseudoangiomatous (almost kaposiform) change hinted at melanocytic origin, which was confirmed with a positive melanoma antigen recognized by T-cells 1 immunohistochemical stain. Histopathological variations in melanocytic morphology include balloon cell formation, pseudoangiomatous change, lipomatous change, nevus of Nanta (osteonevus) with osseous metaplasia, neurotization, cartilaginous nevus, calcification, increased elastic tissue, psamomma body formation, amyloid deposition, eczematous changes (Meyerson nevus), granular cell change and ancient change/atypia. Mucin deposition, tubule and pseudoacini formation, and now discrete adenoid cystic-like "glands" may also be seen, all of which are important to recognize to avoid misdiagnosis.