Abdominal wall metastasis from colorectal carcinoma

PET CT prior to Lt external iliac lymph node resection.

FDG avid node left external iliac chain.

Restaging CT after Lt external lymph node resection

The previously demonstrated soft tissue mass in the left iliac fossa has beensuccessfully resected. There is no evidence of a recurrent mesenteric mass.There are surgical changes seen within the overlying left anterior abdominal wall. Inaddition there is thickening of the musculature in the left anterior abdominal wall inthis region, with the impression of a possible low density, rim enhancing lesionwithin the musculature. This has a maximum diameter of 21 mm and may represent a focalc ollection.

Note is made of a surgical anastomotic line in the right colon. There is no evidenceof recurrent mass in this region.There is impression of diffuse bowel wall thickening over long segment extending fromthe rectosigmoid junction to the anal verge. This may be within normal limits althougha mass cannot be excluded. The remainder of the bowel is unremarkable.

The liver, spleen, pancreas, gall bladder, both adrenals and both kidneys are grosslynormal.The prostate is markedly enlarged and heterogenous.There is moderate calcific atherosclerosis in the abdominal aorta.There is no free fluid in the abdomen and pelvis.There is no significant abdominal, pelvic or inguinal lymphadenopathy.

There are degenerative changes in the lumbar spine but no sinister osseous lesions.

CONCLUSION:

1. 2.1 cm rim enhancing lesion within the left lateral anterior abdominal wallmusculature. This may represent a collection or mass. Further evaluation with ultrasound is recommended.

2. Marked prostatomegaly.

3. Diffuse wall thickening throughout the rectum and rectosigmoid junction. A mass cannot be excluded and direct visualization with colonoscopy is recommended.

Diagnostic US following restaging CT

Irregular and hypoechoic soft tissue mass in left groin, immediately deep to incisional scar.

US GUIDED BIOPSY

Using sterile precautions, the left groin mass was biopsied with an 18G system. Two cores were obtained and Rapid On Site Evaluation (ROSE) confirmed adequacy of specimen. No immediate complications.

Serial sections of the core biopsies show infiltration of fibrous connective tissue by poorly differentiated adenocarcinoma. This consists of irregularly shaped glandular structures lined by markedly pleomorphic cuboidal and columnar epithelial cells. These have irregularly shaped hyperchromatic and vesicular nuclei with a variable amount of pale cytoplasm. Solid aggregates of similar appearing atypical cells are also noted. Frequent mitotic figures are identified and there are foci of tumor necrosis. The features are consistent with an origin from colorectum.

DIAGNOSIS: "Left groin mass core biopsies": Infiltration of fibrous tissue by poorly differentiated adenocarcinoma with features consistent with an origin from colorectum. Immunohistochemistry shows strong nuclear staining for CDX2 in tumor cells and strong cytoplasmic staining for carcinoembryonic antigen (CEA) and cytokeratin CK20. No staining for TTF-1 or cytokeratin CK7 is seen in tumor cells. This profile indicates an origin of tumor from colorectum.