Unusual Histologic Variant of a Low-Grade Fibromyxoid Sarcoma in a 3-Year-Old Boy with Complex Chromosomal Translocations Involving 7q34, 10q11.2, and 16p11.2 and Rearrangement of the FUS Gene

Abstract

Low-grade fibromyxoid sarcomas are rare, histologically deceptive, cytologically bland tumors that are infrequently encountered in pediatric patients. Our knowledge of histologic spectrum of these tumors is limited. A histologically unusual variant of a low-grade fibromyxoid sarcoma arising in a 3-year-old boy and containing islands of cohesive epithelioid cells is described. The diagnosis was, given the patient's age and the presence of epithelioid islands, very difficult and was verified by the presence of 3-way chromosomal translocations involving 7q34, 10q11.2, and 16p11.2 by rearrangement of the FUS gene and by immunoreactivity for mucin 4.

Deeply located low-grade fibromyxoid sarcoma with FUS-CREB3L2 gene fusion in a 5-year-old boy with review of literature

“…Recently, LGFMS was shown to be associated with gene fusions involving CREB3-family genes that encode members of the basic leucine zipper family of transcription factors [2]. The majority of LGFMS cases (95%) have a fusion of the FUS-CREB3L2, and a minority of cases (5%) have a FUS-CREB3L1 gene fusion.…”

“…Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue tumor that typically affects young to middle-aged adults [1,2]. The median age of onset for LGFMS is 34 years [3], although patients of any age can be affected, and 13-19% of cases occur in patients 18 years and younger [3,4].…”

“…The median age of onset for LGFMS is 34 years [3], although patients of any age can be affected, and 13-19% of cases occur in patients 18 years and younger [3,4]. However, LGFMS is rare in children during the first 5 years of life [2]. To the best of our knowledge, the youngest case of LGFMS is a tumor arising from the cheek in a 22-month-old girl [4].…”

“…Although, LGFMS is negative for most immunohistochemical markers, a recent study identified up-regulation of the mucin 4 (MUC4) gene in LGFMS compared with histologically similar tumors and lesions [8,9], and MUC4 immunostaining was a sensitive and specific marker of LGFMS in the appropriate morphologic context [2,5]. Additionally, it has been described that claudin-1, which was associated with tight junction protein, and epithelial membrane antigen (EMA) were negative for LGFMS [10] with exceptional positivity for LGFMS with perineuriomatous component [11].…”

“…Several recent studies demonstrated that greater than 90% of LGFMS have a balanced chromosomal translocation t (7;16) (q32-34;p11) leading to the fusion of the FUS and CREB3L2, while a minority of cases have a t(11;16) (p11;p11) translocation leading to the fusion of the FUS and CREB3L1 [1,2,5–7,12,13]. In one report, a small number of LGFMS cases contained EWSR-CREB3L1 gene fusions [5].…”