Mucinous adenocarcinoma arising from chronic perianal fistula mimicking horseshoe abscess

Abstract

Perianal fistulae are commonly seen clinical entity. Development of malignancy within a perianal fistula is rare. Even rarer is the development of mucinous adenocarcinoma in a chronic fistula-in-ano. Only a handful of such cases have been reported in the past. A case of mucinous adenocarcinoma arising in chronic perianal fistula in a 34-year-old woman is being described. She presented with complaints of perineal fullness, pain and recurrent pus discharge from perianal fistula for 4 years. On radiological workup, a large solid-cystic pelvic mass was seen in relation to the fistula. On MRI, the lesion was mimicking a large horseshoe abscess. Transrectal ultrasound-guided biopsy and subsequent histopathological examination confirmed the presence of mucinous adenocarcinoma with tumour cells immunopositive for CK7 and CK20.

An Association of Mucinous Adenocarcinoma With Chronic Peri-Anal Fistula: A Brief Review of Pathophysiology of Rare Tumor

“…In another study, Prasad et al reported the origin of MA in a patient with chronic anal fistula, which was confirmed by transrectal ultrasound-guided biopsy and consecutive histopathological examinations. The study summed up three criteria needed for the diagnosis of MA: (1) the presence of fistula ought to usually precede that of carcinoma by 10 years, (2) any tumorous association of the rectum or anal canal should only be a secondary extension of the primary mass involving the fistula, and (3) internal opening of the fistula within the rectum or anal canal should not be included, as shown in Figure 4 [ 1 ].…”

“…Peri-anal fistulas can be found frequently in the clinical setting, but the malignant transformation of these fistulas is not common. The development of anal mucinous adenocarcinoma (MA) from chronic peri-anal fistula is rare, and only a few such cases have been reported in the past [1]. Anal fistulas usually develop from an anal abscess, and the background of the fistula is regularly very typical.…”

“…The occurrence of anal fistula is higher in females than in males with 50% and 31%, respectively [3]. 1 2 3 3 Cancer of the peri-anal fistula is an erratic disease. It is predominantly associated with chronic anal fistula.…”

“…Three-point criteria presented by Prasad et al emphasizing an association of mucinous adenocarcinoma with chronic peri-anal fistula[1] …”

Mucinous adenocarcinoma arising from chronic perianal fistula—a multidisciplinary approach

“…Distant metastases are rare in MA, and tumor spread is usually lymphatic, being the inguinal nodes the most frequent site of metastases (21). According to the published data, prognosis seems to be worse when the tumor is larger than 5 cm size, carcinoembryonic antigen is elevated, or lymph nodal or haematogenous metastases are present at the time of diagnosis (25,26), finding reported survival rates of 2-48 months (27).…”