Clinicopathology of adenocarcinoma originating from the anal gland with immunohistochemical expressions of GATA3 and TTF-1: a case report and literature review

Adenocarcinoma originating from the anal gland with immunohistochemical expression of GATA3 and TTF-1 (ACAGGT) is a rare entity. This report describes an 80-year-old female patient who detected a perianal mass without an obvious cause 10 years prior and presented to our hospital (Hangzhou, China) with local pain lasting 3 days. Preoperative B-ultrasound revealed a heterogeneous hypoechoic area in the right perianal region, adjacent to the subcutaneous tissue. Pelvic magnetic resonance imaging (MRI) with contrast enhancement showed an abscess on the right side of the anal canal. Under general anesthesia, the patient underwent lesion resection and anal sphincteroplasty. Pathological examination demonstrated that the tumor exhibited glandular and solid components with invasive growth. The stromal tumor-infiltrating lymphocyte (TIL) score was moderate (30%). Immunohistochemical staining suggested the following results: CK7 (+), GATA3 (90%, +), TTF-1 (10%, +), Vimentin (-), CK20 (-), and CDX-2 (-). The programmed death ligand 1 (PD-L1) combined positive score (CPS) was 5. Additionally, molecular testing failed to detect common driver gene mutations (e.g., KRAS/NRAS/BRAF), and the tumor was microsatellite-stable (MSS). The patient received postoperative radiotherapy. At 6 months of follow-up, metastasis to the right inguinal lymph nodes was identified.