Angiomyofibrosarcoma: a rare ischiorectal fossa swelling

Abstract

A33-year-old woman presented with a painful lump in the right gluteal region, 7 months after normal vaginal delivery of her child. There was no history of altered bowel habits, bleeding per rectum, dyspareunia or difficult labour. On examination she was afebrile. Local examination revealed asymmetry with a tender lump in the right gluteal region and some redness of the overlying skin. Rectal examination revealed a tender right lateral rectal wall. Magnetic resonance imaging (Figure 1) revealed a 12×8×8 cm complex ‘cyst’ in the right ischiorectal fossa displacing the levator ani upward and the rectum medially, with an apparent pseudo capsule. In the T1-weighted sequences, it had higher signal intensity than the bladder. On T2-weighted sequences, the lesion was of very high intensity. Also in the surrounding fat were multiple linear foci of high intensity, representing oedema or increased vascularity. In view of the location, it was suggested that this could be an abscess. Examination under anaesthesia revealed a boggy swelling in the ischiorectal fossa. An incision to drain this abscess revealed no pus, however, a soft fatty lump protruded from the incision. The incision was extended and a soft tissue mass 12 cm in diameter was enucleated. The cavity was packed and skin incision closed after 3 days. Histopathology revealed an angiomyxoid tumour, extending to the resection margins. Subsequently she was sent to a specialist centre. Computed tomography of the chest was normal. After discussion with the patient about the possibility of incontinence and stoma, re-excision was performed. Histology suggested low grade, sarcomatous changes in a pre-existing myofibroblastic lesion, either angiomyxoma or angiomyofibroblastoma. Immunostaining was positive for desmin and weakly positive for actin and calponin. Staining for caldesmin and myogenin were negative. CD34 was present in few scattered spindle cells. No adjuvant therapy was given. She had one admission since then with a wound collection, which was drained.

Leiomyosarcoma of the ischiorectal fossa: report of a novel sphincter and sciatic nerve sparing simultaneous trans-abdominal and trans-gluteal resection and review of the literature

“…The first reported case of a sarcoma in the ischiorectal fossa was in 1988 by Long Pretz et al of a liposarcoma [ 4 ]. Since then, only a handful of cases have been reported, with the second case not published until 2003 of an angiomyofibrosarcoma [ 5 ]. Other reported sarcomas include a malignant peripheral nerve sheath tumour (MPNST) [ 6 ] and a spindle cell sarcoma [ 7 ].…”

Resection of ischiorectal fossa tumors – surgical technique

“…1 They have a gelatinous appearance and are locally invasive. 5 Malignant peripheral nerve sheath often exhibits areas of benign appearance indistinguishable from fibromatosis. One feature is that such tumors can also be focal, explaining the original diagnosis errors.…”