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

Abstract

BackgroundLow-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue tumor typically affecting young to middle-aged adults. Despite its otherwise benign histologic appearance and indolent nature, it can have fully malignant behavior, and recurrence and metastasis may occur even decades later.Case historyWe report a case of LGFMS in the left lower leg of a 5-year-old Japanese boy. A magnetic resonance imaging (MRI) uncovered a well-demarcated intra-gastrocnemial tumor measuring 27 × 20 mm with a slightly high intensity on T1WI and heterogeneously high intensity on T2WI. Histologically, the tumor was composed of bland spindle-shaped cells with a whorled growth pattern. The tumor stroma was variably hyalinized and fibromyxoid with arcades of curvilinear capillaries and arterioles with associated perivascular fibrosis. Although LGFMS is known to affect children under 18 years of age, it is extremely rare in infants and children under 5 years of age. Despite the young age, this patient was accurately diagnosed by the typical histology and the detection of a FUS-CREB3L2 gene fusion.ConclusionAlthough LGFMS in children tends to be located superficially, this case presented with an intramuscular tumor in the region of the gastrocnemius. To the best of our knowledge, this is the first case of deep LGFMS arising in a child younger than 5 years of age. The patient is still alive with no evidence of the disease 4 months after diagnosis.Virtual SlidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000_2014_163

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

“…For instance, we examined several markers such as desmin, S-100, CD34, and EMA, but the results were negative (data not shown). The findings are consistent with the published literatures [2, 10, 15]. Doyle and colleagues identified MUC4 as a highly sensitive and specific marker for LGFMS through gene expression profiling.…”

“…The anatomic locations of LGFMS are common in the soft tissues of the upper limbs, lower limbs, and trunk wall [2, 5]. LGFMS occurring in the perineal space is extremely rare and only a few cases have been reported [10–17].…”

“…Despite its deceptively benign appearance, LGFMS has a high tendency for local recurrence and late distant metastasis, mainly to the lung [2, 3]. The histological appearance of LGFMS is characterized by the presence of alternating fibrous and myxoid area in a whorled growth pattern [3].…”

“…Although LGFMS is common in middle-aged adults, 13–19% of cases occur in 18 years and younger. To date, the youngest reported case was 22-month-old [2, 4, 5]. …”

Low‐grade fibromyxoid sarcoma of acral sites: Case report and literature review

“…Clinically, LGFMS mostly affects young adults around the third decade and can occur in the pediatric age group after the age of 5 (13%‐19% of cases) . A male predilection is seen in the pediatric age group whereas in adults, some studies show no gender difference while others report the same trend seen in the younger population . Typically presenting as a deep‐seated (below fascia) soft tissue painless mass mostly affecting the extremities and trunk .…”