Clinicopathologic features of primary scrotal cutaneous mucinous carcinoma associated with acantholytic extramammary Paget's disease

SHEN Yan-ling; LIU Xue-qing; SU Yu-jiao; YANG Wen-sheng

doi:10.3969/j.issn.1007-8096.2025.05.010

Abstract：Objective To investigate the clinical and histopathological features of primary cutaneous mucinous carcinoma with acantholytic extramasmary Paget's disease.Methods A clinical,histological,and immunohistochemical analysis of 1 case of primary mucinous carcinoma of skin with epidermal Paget's disease is reviewed,and the clinicopathological features and differential diagnosis are summarized based on a review of relevant literature.Results The patient was a male,43 years old,who presented with persistent skin ulceration in the scrotum for several months.The specimen was a piece of skin with overlying epidermis showing ulceration,and subcutaneous grayish-white,gelatinous nodules with clear borders.Histologically,there was hyperkeratosis and parakeratosis of the epidermis,thickening of the granular layer,partial detachment of the dermis,formation of intraepidermal fissures,and the presence of tufted basal cells.Paget cells were scattered or found in cyst-like aggregates in the dermis.In the dermis,there was mucinous carcinoma with well-defined margins,no capsule,and a lobulated appearance with abundant mucin and mucinous lakes.Immunohistochemistry showed that Paget cells were diffusely positive for PCK7,PCK8,CEA,and EMA,while PCK20,GCDFP-15,HMB-45,and MelanA were negative.p63 was positive in the basal cells,and Ki-67 was approximately 70%positive.In the mucinous carcinoma area,PCK7,PCK8,and EMA were diffusely strongly positive,GCDFP-15 was partially weakly positive,CEA was focally positive,p63 and CK5/6 were focally muscular epithelial positive,PAS was positive,PCK20,CDX-2,TTF-1,GATA3,S-100,HMB-45,and MelanA were negative,and Ki-67 proliferation index was approximately 10%.Conclusion Primary mucinous carcinoma with dermal involvement and Paget-like epidermal changes is a rare entity,and increasing awareness of this condition can help avoid misdiagnosis and missed diagnoses.