Is histopathological evidence really essential for making a surgical decision about mucinous carcinoma arising in a perianal fistula? Report of a case

Abstract

We report an unusual case of mucinous adenocarcinoma of the anus associated with a chronic anal fistula, treated successfully by abdominoperineal resection (APR). Although multiple biopsies failed to reveal any histological evidence of malignancy, cancer was diagnosed from the mucin obtained for cytology. Subsequent histological examination of the resected specimen revealed clusters of cancer cells floating in a mucous lake, suggesting that it would have been difficult to acquire the cells in a biopsy sample. Conversely, the presence of mucin lakes and globules in specimens drained from the region of perianal sepsis may have been histologically informative for diagnosis. Thus, although biopsy of the lesion is undoubtedly essential for diagnosis, it often fails to provide enough information to make a definite diagnosis of mucinous carcinoma. This case illustrates that clinicians should base their decision on whether to perform surgery on clinical manifestations, imaging findings, and cytology of mucin obtained by drainage when it is difficult to obtain malignant cells by biopsy.

Mucinous adenocarcinoma of perianal region: an uncommon disease treated with neo-adjuvant chemo-radiation

“…Perianal mucinous adenocarcinoma is a very uncommon entity accounting for only 2% to 3% of all gastrointestinal tumors (1,2) and 3% to 11% of perianal cancers (4). This entity poses a diagnostic and therapeutic dilemma as till date no clear consensus has been reached regarding its etiopathogenesis and disease classification thereby hindering subsequent management.…”

MRI Findings of Mucinous Adenocarcinoma Arising From Perianal Fistula: Report of Two Cases

“…Results of needle biopsies are usually not conclusive because the cancer cells float in mucous lakes, and they cannot be obtained easily. The biopsy of the external opening of the fistula is also not definitive in most cases (9). MRI is the most accurate imaging modality to evaluate the perianal anatomy, to visualize the extent of the perianal abscess, and the fistulous tract, and to diagnose malignant transformation (7).…”

Diagnostic implications of MR imaging for mucinous adenocarcinoma arising from fistula in ano

“…However, the biopsy of the external openings of the fistula is not conclusive and very often misleading because the tissue taken is very superficial and only reveals an inflammatory reaction, especially when scarring and fibrosis are present. Thus, biopsy of the lesion is undoubtedly essential for diagnosis, but it often fails to provide enough information to make a definite diagnosis of mucinous carcinoma [4].…”