Low-grade fibromyxoid sarcoma of the external anal sphincter: a case report

Abstract

BackgroundLow-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue tumor that has a tendency to grow in the deep soft tissue of the trunk and extremities. Despite its benign appearance, the tumor has a high recurrence rate and metastatic potential. LGFMS in the perineal space is rare, and only a few cases have been reported. We present the first case of LGFMS to be located at the external anal sphincter.Case presentationA 27-year-old male patient admitted to our Surgical Department with perianal pain and swollen for a year. The digital rectal examination revealed a perianal mass. Oral metronidazole and analgesia were prescribed on suspicion of perianal abscess failed to alleviate the symptom; hence, the patient was scheduled for surgery. Intraoperative diagnosis revealed an encapsulated tumor in the external anal sphincter that extended from the perianal region orally to the pararectal space. The results of immunohistochemistry (MUC4 staining) and FUS gene rearrangement by fluorescence in situ hybridization confirmed the diagnosis of LGFMS.ConclusionsThis case is unique in terms of the location of the rare soft tissue tumor. Although LGFMS is considered low grade, its unpredictable behavior necessitates a long-term follow-up.

Low-Grade Fibromyxoid Sarcoma in the Left Gluteal Region Presenting as Sciatic Nerve Pain

“…The benefit of radiotherapy remains questionable and is performed only in patients at risk for recurrence or metastasis such as margin positivity, tumor location, and tumor size [10]. Chemotherapy is reserved for patients whose tumors recur locally or spread to distant sites [14] [15].…”

Case: Pediatric paratesticular soft tissue perineurinoma — A rare entity

“…CD34 and claudin-1 further confirm the diagnosis, while the absence of desmin and S-100 are equally as significant 1,2 . EMA stains are positive in both perineuriomas and LGFMS, but a negative MUC4 stains excludes LGFMS because it is a very specific and sensitive marker for LGFMS 3,5 . Grossly, perineuriomas have a characteristic focally whorled growth pattern and histologically, elongated and thin spindle cells can be seen 1 .…”

Spindle cell proliferations of the sigmoid colon, rectum and anus: a review with emphasis on perineurioma

“…Other rare malignant spindle cell tumours described at this site include embryonal rhabdomyosarcoma, angiosarcoma, dermatofibrosarcoma protruberans, Kaposi's sarcoma, de‐differentiated liposarcoma, low‐grade fibromyxoid sarcoma, sarcomatoid/spindle cell carcinoma and sarcomatoid renal cell carcinoma …”