Mullerianosis of inguinal lymph nodes: report of a case

We report a case of florid mullerianosis involving inguinal lymph nodes, a simulator of metastatic adenocarcinoma. The patient was a 48-year-old woman with symptomatic leiomyomas and enlarged right inguinal lymph nodes. Microscopically two lymph nodes were partially or completely replaced by cystically dilated and small glands, many of which contained mucin. The larger of the two lymph nodes was completely replaced by cystically dilated structures and long branching tubular glands that focally displayed well-defined lobular and papillary patterns. The glands were lined predominantly by a single layer of columnar cells similar to those of the endocervical epithelium. The columnar cells had bland basal nuclei and abundant mucin-containing cytoplasm. Admixed with these cells were others similar to those of tubal epithelium. Some of the glands were partially surrounded by a cellular ovarian-like stroma. There was focal cytologic atypia but no mitotic figures were seen. There was also focal oxyphil cell metaplasia with atypical hobnail cells. Some cystically dilated glands that contained abundant mucin were lined by flat epithelial cells. Because of gland rupture, mucin extravasated into the stroma but did not elicit a desmoplastic response. Surgical pathologists should be aware of mullerianosis in lymph nodes to avoid confusing it with metastatic adenocarcinoma.