Primary Low-grade Fibromyxoid Sarcoma Research Articles

Primary low-grade fibromyxoid sarcoma of the large intestine with lung metastases: A case report and review of the literature

A 70-year old man had multiple lung nodules detected on a computed tomography (CT) performed as part of the work-up for an isolated episode of hematuria of several hours' duration. A CT-guided lung biopsy disclosed a morphologically undifferentiated neoplasm, that could not be further subclassified despite an extensive immunohistochemical panel.Four years previously the patient had undergone a left hemicolectomy in another institution to resect a 4.7 cm polypoid ulcerated area in the splenic flexure. The slides from that resection were retrieved for review at our institution. There was a variably cellular, diffuse spindle cell neoplastic proliferation involving the submucosa, muscularis propria and subserosa of the large bowel, composed of elongated spindle cells, with small, inconspicuous nucleoli, arranged in intersecting fascicles. Occasional areas of the tumor showed myxoid stroma. Mitotic activity was low.Immunohistochemistry showed strong and diffuse cytoplasmic staining for MUC4 in both the large bowel and lung tumors. Molecular profiling identified a FUS-CREB3L1 fusion gene.The constellation of morphological, immunohistochemical and molecular features are of low-grade fibromyxoid sarcoma (LGFMS) of the large bowel, with metastatic fibromyxoid sarcoma to the lung.LGFMS is a malignant, often late-metastasizing tumor, with a misleadingly bland histological appearance, that typically arises in the deep soft tissues of the proximal extremities or trunk of young adults. Accurate classification, requiring morphology and ancillary tests, is required for appropriate clinical follow-up and treatment of patients.

Primary Low-Grade Fibromyxoid Sarcoma of Kidney-an Extremely Rare Entity.

Renal LGFMS is an extremely rare tumor. So far, only four cases have been reported in literature. LGFMS are indolent tumor with distinctive histopathological features with potential for late recurrences and metastasis. The diagnosis is made on histopathological examination and supported by immunohistochemical analysis. A 35-year-old young male was presented with flank pain and lump and diagnosed as low-grade fibromyxoid sarcoma after surgery on immunohistochemical analysis. This is the fifth case of renal LGFMS and we presented the review of literature. Radical surgery remains the primary treatment modality. Long follow-up is mandatory.

Low-grade fibromyxoid sarcoma: an unusual cardiac location

We report the unusual cardiac localization of a primary low-grade fibromyxoid sarcoma of the right ventricle in a 57-year-old woman. Histological examination revealed a prevalent myxoid appearance with whorling growth pattern of small or spindle cells with bland features alternating with rare more collagenous hypocellular areas with rare atypical cells. Genomic polymerase chain reaction of genomic DNA revealed the typical FUS/Creb3L2 fusion gene products typical of low-grade fibromyxoid sarcoma. The tumor was surgically removed and recurred after 7 years as high-grade pleomorphic sarcoma. The patient died 6 months after the clinical manifestation of recurrence. Low-grade fibromyxoid sarcoma of soft tissues is a rare, distinctive variant of fibrosarcoma-typically arising in deep soft tissue of lower extremities and trunk-that rarely metastasizes. Clinically, low-grade fibromyxoid sarcoma is characterized by a longer survival rate compared to other sarcomas, suggesting its consideration in the differential diagnosis of cardiac tumors with a myxoid appearance.

Myxoid Solitary Fibrous Tumor of the Central Nervous System

Solitary fibrous tumors (SFTs) most commonly occur in the pleura, but may also occur in the central nervous system (CNS). Among the numerous cases of CNS SFT that have been reported, totaling to more than 220 cases, the myxoid SFT of the CNS has been the least recognized and most misleading subtype.1 Differential diagnosis from chordoid or myxo-chordoid meningioma, myxoid peripheral nerve sheath tumor, metastatic or primary low-grade fibromyxoid sarcoma, primary intracranial myxoma, and metastatic tumor from a cardiac primary tumor is therefore necessary. Here, we present a case of a myxoid SFT located in the tentorium cerebelli. A 45-year-old woman presented with headache, general weakness, and impaired vision. A magnetic resonance imaging scan revealed a lunulating, contoured, enhancing mass measuring 7.0×6.0×2.0 cm with hemorrhagic foci, located in the right posterior parietal and temporooccipital convexities. Under the diagnosis of meningioma, open craniotomy, right parietotemporooccipital, and subtotal tumor removal was performed. Upon observation, many firm, rubbery, and bosselated tumor fragments, tan-white in color, were identified. The cut surface was relatively homogeneous, with a whitish fibrotic appearance and softer areas of gelatinous myxoid change, approximately 50%. Necrotic areas were not observed. Microscopic examination revealed a predominantly hypocellular area in the myxoid stroma, intervening with foci of a morphologically typical, densely cellular SFT with spindle cells and collagenous stroma (Fig. 1). In the hypocellular and myxoid areas, a proliferation of cytologically bland spindled cells was randomly arranged in a loose myxoid matrix, forming interconnecting strands, and resulting in degeneration. The neoplastic cells had oval to elongated nuclei, with evenly distributed chromatin, inconspicuous nucleoli, and scant pale cytoplasm. Immunohistochemically, the tumor cells showed a strong expression of CD34, vimentin, Bcl2 and CD99, but were negative for epithelial membrane antigen (EMA), pan-cytokeratin, and glial fibrillary acidic protein (GFAP). The Ki-67 labeling index was lower than 4%. On the basis of these findings, the final diagnosis was myxoid SFT. Fig. 1 Histologic findings. Myxoid stroma with focal ropy collagen in a rich vascularized tumor (A), moderately cellular area exhibiting spindle cells and collagenous stroma (B), and strong immunoreactivity for CD34 (C). Myxoid SFT of the CNS is an extremely rare tumor and differential diagnosis may be difficult to achieve owing to confusion with several other myxoid spindle cell neoplasms. Indeed, myxoid SFT of the CNS must be differentiated from chordoid or myxo-chordoid meningioma, myxoid peripheral nerve sheath tumor, metastatic or primary low-grade fibromyxoid sarcoma, primary intracranial myxoma, meningeal hemangiopericytoma and metastatic tumor from a cardiac primary. Immunohistochemistry has proven to be a useful tool in attaining an accurate diagnosis. SFT of the CNS commonly shows strong positivity for CD34, Bcl2, and vimentin, but is negative for S-100 protein, GFAP, and EMA. Negativity for S-100 rules out chordoid or myxo-chordoid meningioma (vimentin+/EMA+/CD34+/S-100-), myxoid peripheral nerve sheath tumor (vimentin+/S-100+/EMA-/CD34-), metastatic or primary low-grade fibromyxoid sarcoma, and primary intracranial myxoma. Positivity for CD34 and Bcl2 may rule out the meningeal hemangiopericytoma (vimentin+/EMA-/CD34-/Bcl2-).2 Through clinical correlation, metastatic cardiac myxoma may be easily suspected. The histogenesis of SFT is still unclear; however, tumor cells were shown to share similar histological features with fibroblasts. Microscopically, there are 3 common elements that appear in SFTs: spindle cells, a dense collagenous matrix, and prominent blood vessels.1 Spindle cells have oval nuclei with scant cytoplasm, and the cell borders are unclear. They may arrange into fascicles with no specific direction, creating a swirling pattern. The collagenous area is variable in size, and takes the form of ropy collagen. Cell density also varies, with hypercellular and hypocellular areas.3 Our case also shows a predominantly hypocellular area with myxoid stroma, and a hypercellular area with collagenous stroma. When fibrous tumors with myxoid nature involve the CNS, proper immunostaining and histologic differentiation should be done for differential diagnosis.