Low‐grade fibromyxoid sarcoma with nuclear pleomorphism arising in the subcutis of a child

Abstract

Low-grade fibromyxoid sarcoma (LGFMS) represents a rare soft tissue tumor that was first characterized in 1987. LGFMS usually presents as a large, deeply situated mass in adults and is characterized by deceptively bland histopathologic features. LFGMS is less common in superficial soft tissue and in children. It is distinctly uncommon for LGFMS to exhibit nuclear pleomorphism. Herein, we present a case of a 10-year-old male who presented with a subcutaneous back mass that displayed features typical for LGFMS as well as scattered large, hyperchromatic and pleomorphic nuclei. The constellation of clinicopathologic features, including the young age of the patient, the small size and superficial location of the tumor and the presence of scattered nuclear pleomorphism are all unusual features for LGFMS. Fluorescent in situ hybridization (FISH) with a break-apart probe for FUS revealed the presence of a FUS gene rearrangement confirming the diagnosis of LGFMS. This case highlights the importance of maintaining a high index of suspicion for LGFMS even in the context of small, superficially-located tumors, pediatric patients or tumors with scattered nuclear pleomorphism.

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

“…The clinical, histological, and genetic information of the previously reported cases are summarized in Table 1 [1,2,4–7,12,13,19–27]. Nine cases up to 5 years of age were found including the present case.…”

“…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].…”

“…Histologically, LGFMS is composed of bland spindle-shaped cells in a whorled growth pattern, arranged in alternating myxoid and collagenized areas along with curvilinear capillaries and characteristic arterioles with perivascular fibrosis. Although most of the tumor cells show benign histological appearance, approximately 10% of the tumor may have scattered large, hyperchromatic and pleomorphic nuclei [1]. Furthermore, approximately 40% of cases have focal areas of hypocellular collagen cores rimmed by epithelioid fibroblasts, referred to as collagen pseudo-rosettes.…”

“…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].…”

Recurrent Low-Grade Fibromyxoid Sarcoma of the Neck: Report of a Case and Review of the Literature

“…As both translocations involve the FUS gene, FISH for FUS genetic rearrangement is an ideal technique for confirming the diagnosis [5,10]. Alternatively, reverse transcriptase polymerase chain reaction (RT-PCR) can also be used to detect either fusion product; such assays have only rarely been proposed to analyze formalin-fixed, paraffin-embedded neoplasm samples [11].…”