53 | MAMMARY PAGET DISEASE WITH OCCULT DCIS: A RARE MALE CASE

M. Fino¹, C. Brunello¹, N. Di Meo¹, I. Zalaudek¹, S. Sola², C. Massone³ | ¹Department of Dermatology and Venereology, University of Trieste, Maggiore Hospital, Trieste, Italy; ²Department of Pathology, Galliera Hospital, Genoa, Italy; ³Department of Dermatology, Galliera Hospital, Genoa, Italy

Mammary Paget disease (MPD) is a rare intraepidermal adenocarcinoma accounting for 1–4% of breast malignancies, usually associated with underlying ductal carcinoma in situ (DCIS) or invasive carcinoma. It is rare in men and may present with atypical clinical features. We report the case of a 74-year-old man presenting with an asymptomatic, asymmetric erythematous plaque with a surrounding brownish pigmented area of the right nipple–areolar complex. Dermoscopic examination revealed non-specific red and white structureless areas with atypical polymorphous vessels, raising suspicion of amelanotic melanoma. Notably, no eczematous changes, erosion, or ulceration of the nipple–areolar complex were present, contributing to diagnostic uncertainty. Histopathological examination of a punch biopsy revealed a predominantly intraepidermal pagetoid proliferation of atypical cells consistent with MPD, with focal invasion of the papillary dermis. Mammography and breast ultrasonography revealed no detectable breast mass or axillary lymphadenopathy. The patient underwent right mastectomy with sentinel lymph node biopsy. Final histopathology confirmed diffuse MPD with focal dermal microinvasion associated with a 5-mm DCIS G1; lymph nodes were negative for metastasis. The final pathological stage was pT1mic pN0(sn)(i−). No adjuvant therapy was indicated, and the patient was enrolled in follow-up. This case highlights an unusual presentation of male MPD. Although histologically consistent with a typical Paget disease, the clinical presentation was atypical due to the absence of the characteristic eczematous changes, erosion or ulceration of the nipple–areolar complex. This clinico-pathological discordance, together with the melanoma-like dermoscopic pattern, represents a relevant diagnostic pitfall.