LAUSR

A 54-year-old woman presented with a mass in the left breast and another in the ipsilateral axilla. Until then, the patient was in her usual state of good health, although she did admit to neglecting an episodic and localized “mild itch” in the ipsilateral nipple (with neither ulceration nor discharge) for the past 6 or so months. A needle core biopsy of the left breast mass showed an invasive ductal carcinoma (Figure 1A), and that of the axilla showed similar metastatic carcinoma in a lymph node. A mastectomy with ipsilateral axillary dissection revealed a 2.8-cm moderately differentiated invasive ductal carcinoma with metastatic involvement in 2 of 12 lymph nodes. No lymphovascular channel involvement by tumor cells was identified. The nipple, entirely submitted for histopathological examination owing to clinical suspicion of Paget disease (raised by the “itch”), showed dense infestation of nearly all cutaneous adnexal pilosebaceous units in the nipple by numerous parasites that spanned up to 0.4 mm (Figure 1B-E; note: parasites in boxes in B). The latter exhibited the archetypal structure of Demodex: a cutaneous mite with 2 fused segments and 4 pairs of legs attached to the first segment (Figure 1F). There was minimal nonspecific lymphocytic infiltrate associated with the mites. The skin of the nipple and underlying lactiferous ducts were otherwise unremarkable. In 1946, Garven was the first to report the presence of Demodex in the nipple. Since then, the mite’s presence (demidicosis) in this location has garnered only occasional attention—at least in the published literature. A prospective study of adult autopsies reported the presence of these parasites in 58 (41.4%) of 140 nipples, and it has been 809415 IJSXXX10.1177/1066896918809415International Journal of Surgical PathologyHoda and Cheng research-article2018