Low Grade Fibro-Myxoid Sarcoma: A Case Report on MUC4 as A Novel Immunohistochemistry Marker to Detect this Benign Mimic of Malignant Neoplasm

Abstract

Dey Sumedha, Das Jayitri, Ara Zeenat, Prabhakar Monika, Ghosh Mallika, Nakra Reena and Lal Vandana

Low-grade fibromyxoid sarcoma(LGFMS) is a rare type of malignant fibroblastic and myofibroblastic tumor that is characterized by benign appearing histologic features but with a paradoxically aggressive clinical course and metastasis. These tumors generally occur in young and middle aged adults. Most common sites of involvement are proximal extremities and trunk and are usually subfascial in-depth. Less common locations include central body sites and superficial soft tissues. It has a male predilection. Here we describe a case of low-grade fibromyxoid sarcoma affecting the left thumb of a 39 year old male . The duration of the disease spans over 2 years with one history of recurrence after excision. On gross examination the specimen was firm, irregular, elongated swelling measuring 3.5 x 2 x 1 cm. Microscopically the tumor was composed of collagenous hypocellular areas alternating with hypercellular myxoid areas in nodules with abrupt transition between the two. Immunohistochemistry revealed strong positivity for Vimentin, CD99, focal SMA and very strong cytoplasmic positivity for MUC4 confirming the diagnosis of low-grade fibromyxoid sarcoma. After initial healing of the surgical wound, the patient went for radiotherapy and there is no recurrence till date. However long-term follow up is necessary as there is history of metastasis that has occurred as long as 45 years after primary excision.

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