Abdominal myoepithelial carcinoma: A rare abdominal wall entity of an uncommon tumor.

Introduction And Importance: Myoepithelial carcinomas are a diverse group of tumors exhibiting myoepithelial differentiation. There have been increasing reports of extra-salivary sites of origin for myoepithelial carcinomas such as soft tissues, bone and visceral areas. Due to this entity's rarity, definite diagnostic and treatment parameters are somewhat limited. We present the case of a myoepithelial carcinoma arising from the abdominal wall, a rare site of origin of an uncommon tumor.

Case Presentation: A 37-year-old gentleman presented to our institution in Oct 2018 with a recurrent abdominal mass for which he underwent wide local excision after completing the workup, which included systemic scans and relevant blood investigations. The histopathology report was consistent with malignant abdominal myoepithelial carcinoma. However, subsequent follow-up scans in May 2019 showed disease progression with the appearance of multiple lung metastases. After a detailed discussion, he was started on Pazopanib 800 mg orally once a day, on which he remained stable till May 2022. It was then when he experienced clinical disease progression confirmed on systemic scans, so he was offered palliative systemic chemotherapy.

Clinical Discussion: Abdominal malignant myoepithelial carcinomas are an infrequent entity. However, this case highlights its critical diagnostic markers and primary and recurrent abdominal myoepithelial carcinoma management.

Conclusion: Abdominal myoepithelial carcinomas, although rare, are also under-recognized. Thus, keeping an index of high suspicion for these tumors and being armed with knowledge regarding the heterogeneity of its features would lead to better diagnostic awareness and documentation, paving the way for better evidence-based treatments.