Rectal squamous cell carcinoma

Case contributed by Hadi Dahhan
Diagnosis certain

Presentation

Hematochezia, diarrhea, and fatigue.

Patient Data

Age: 75 years
Gender: Male

Rectal wall thickening with associated infiltrative rectosigmoid mass, invading/extending into the mesorectal fat, posterior pelvic sidewall, piriformis muscle, prostate gland, and posterior bladder wall near the insertion of the right ureter. The latter has resulted in right hydroureteronephrosis.

Prominent perirectal lymph nodes. Subcentimeter left iliac chain lymph node.

Subcentimeter hypodense foci in the liver.

Multiple right renal cysts measuring up to 7.2 cm in length. There are calcific densities which likely represent vascular calcifications or, less likely, non-obstructing calculi.
Small left kidney.

Histopathology

Microscopic: biopsy shows fragments of colonic mucosa with regenerative changes along with ulcerated fragments of invasive squamous cell carcinoma. The tumor cells are positive for p40 immunostain while being negative for CDX-2, supporting the diagnosis. 

Case Discussion

Squamous cell carcinoma of the rectum is a rare malignancy that has been associated with chronic inflammation and infection 1. This case involves a very large, locally advanced rectal/anal cancer that is clinically classified as cT4bN2Mx and, at a minimum, corresponds to AJCC stage IIIC rectal squamous cell carcinoma. The tumor exhibits moderate to poor differentiation and has squamous cell histology. It is located within 1 cm of the anal verge, as observed during the colonoscopy. The tumor has extended to the bladder and pelvic sidewall, rendering it inoperable. Surprisingly, the pathology reveals squamous cell carcinoma (SCC). Consequently, the patient's only treatment option is a combination of radiation therapy with palliative intent.

Co-author: Hashem Elessawy, DO

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