Rectal adenocarcinoma presenting with thigh muscle metastasis as the only metastatic site.

Rectal adenocarcinoma presenting with thigh muscle metastasis as the only metastatic site.

BMJ Case Rep. 2019 Jan 22;12(1):

Authors: Doroudinia A, Mehrian P, Dorudinia A, Kaghazchi F

Abstract
Rectal carcinoma with metastasis to skeletal muscle is a rare finding. According to literature review, 17 cases of skeletal muscle metastasis from colorectal carcinoma have been documented where only six cases were rectal carcinomas.We discuss a case of a middle-aged man with a known history of high-grade mucinous adenocarcinoma of the rectum, status post abdominoperineal resection followed by adjuvant radiotherapy and chemotherapy. During the planned chemotherapy course, a right proximal thigh subcutaneous mass was incidentally found which on subsequent biopsy proved to be metastatic from rectal primary site. On subsequent 18F-FDG (Fluorodeoxyglucose) positron emission tomography (PET)/CT scan after completion of chemotherapy for the purpose of treatment response evaluation, only FDG-avid lesion was residual right proximal thigh metastatic mass without involvement of other common sites, such as liver and lung. In this case, the 18F-FDG-PET/CT scan was able to exclude additional metastatic sites and also evaluate the patient's treatment response.

PMID: 30674489 [PubMed - in process]