Extramammary Paget's Disease of the Scalp with an Underlying Atypical Meningioma-A Case Report and Review of the Literature.

Extramammary Paget's disease (EMPD) is a rare adenocarcinoma originating from apocrine glands, primarily affecting the anogenital and axillary regions. Ectopic EMPD, occurring in non-apocrine sites such as the scalp, is exceptionally uncommon. We report a case of ectopic EMPD of the scalp distinguished by its association with an intraosseous atypical meningioma, a previously unreported finding. A 70-year-old female presented with a persistent 15 cm erythematous, alopecic scalp lesion that had been misdiagnosed for a decade. Histopathological analysis confirmed ectopic EMPD, while imaging identified an adjacent intraosseous meningioma. Surgical resection was performed for the meningioma, and radiotherapy was selected as the treatment modality for EMPD. Due to its clinical resemblance to inflammatory dermatoses, ectopic EMPD is often underrecognized, underscoring the critical role of histopathology and immunohistochemical markers in diagnosis. Given its potential association with malignancies, comprehensive systemic evaluation is warranted. The high recurrence rate following surgical excision necessitates consideration of alternative therapeutic approaches, including radiotherapy, Mohs micrographic surgery, or photodynamic therapy. This case highlights the necessity for heightened clinical awareness of atypical scalp lesions and underscores the importance of thorough diagnostic assessment. Further research is needed to clarify the relationship between EMPD and other neoplasms and to optimize management strategies.