Myxoinflammatory fibroblastic sarcoma - Report of two uncommon tumors occurring at classical and unusual sites
Arundhati, Bharat Rekhi, Sangeeta B Desai, Nirmala A Jambhekar
Department of Pathology, Tata Memorial Hospital, Parel, Mumbai, India
Date of Web Publication 6-Jan-2012
Arundhati, Rekhi B, Desai SB, Jambhekar NA. Myxoinflammatory fibroblastic sarcoma - Report of two uncommon tumors occurring at classical and unusual sites. Indian J Pathol Microbiol 2011;54:843-4
Arundhati, Rekhi B, Desai SB, Jambhekar NA. Myxoinflammatory fibroblastic sarcoma - Report of two uncommon tumors occurring at classical and unusual sites. Indian J Pathol Microbiol [serial online] 2011 [cited 2022 Jan 18];54:843-4. Available from: https://www.ijpmonline.org/text.asp?2011/54/4/843/91517
Myxoinflammatory fibroblastic sarcoma (MFS), synonymous with inflammatory myxohyaline tumor of distal extremities with virocyte-like cells, is a unique low-grade sarcoma that predominantly occurs in distal extremities of adults and displays characteristic histopathological features. [1],[2],[3] Lately, MFS has been uncommonly documented at nonacral sites. [4],[5] Herein, we present two cases of MFS occurring at acral and nonacral sites, respectively.
A 40-year-old lady referred to us with history of a gradually developing lesion in her hand that was excised elsewhere and diagnosed as giant cell tumor (GCT) of the tendon sheath.
Another, 45-year-old lady referred with a neck swelling that was excised elsewhere.
In both cases, slides and paraffin blocks were submitted to us for review.
Grossly, the first lesion measured 3 × 2.5 × 2.5 cm. Cut surface was solid, gray-white.
Microscopically, both cases showed an infiltrating tumor with myxoid and fibrous nodules, comprising fibroblastic and inflammatory cells, including lymphocytes, plasma cells, macrophages, and eosinophils, the latter numerous in the second tumor [Figure 1] a, e, f. Interspersed were cells with enlarged nuclei and prominent nucleoli, reminiscent of virocyte-like intranuclear inclusions or Reed-Sternberg-like cells [Figure 1] b, g). Focal hemosiderin deposition was noted. Additionally, pseudolipoblastic cells were identified in the first case ([Figure 1] a, inset). There were no mitoses or necrosis in either tumor. On immunohistochemistry (IHC), the first tumor was positive for vimentin, CD34, and CD68 ([Figure 1] c, d), while negative for desmin. MIB-1 labeling index was low (2-3%). The second tumor ([Figure 1] e to g) was positive for vimentin and negative for SMA, desmin, MyoD- 1, S100-P, CD34, CD15, CD30, and Alk1. Diagnosis of MFS was offered in both cases [Figure 1]. As the sections from margins were not submitted, comments regarding types of resections could not be made.
Figure 1: (a) Nodules of myxoid areas and inflammatory cells. (Hematoxylin and eosin, ×200). Inset: Pseudolipoblast. (b) Cellular area comprising tumor cells with prominent nucleoli, simulating virocyte-like inclusion (arrow). (Hematoxylin and eosin, ×400). Inset: Prominent nucleoli. (c) CD34 positivity. (DAB, ×400). (d) Focal CD68 positivity. (DAB, ×400). (e) Case 2. Alternate cellular and myxoid areas. (Hematoxylin and eosin, ×100). (f) Several inflammatory cells, including numerous eosinophils. (Hematoxylin and eosin, ×200). (g) Interspersed pleomorphic cells. (Hematoxylin and eosin, ×400). Inset: Pleomorphic cells with irregular nuclei and prominent nucleoli. (Hematoxylin and eosin, ×1000)
MFS, on histopathology, comprises, alternate myxoid and fibrous nodules, a mixed inflammatory component, rich in eosinophils, pleomorphic, virocyte-like cells, and pseudolipoblasts. This tumor has tendency for recurrences, but rare metastasis and is, therefore designated as a low-grade sarcoma. [1],[2],[3],[4] Clinicopathologically, it is either misdiagnosed as a ganglion cyst and GCT of the tendon sheath or as a malignant tumor like an inflammatory malignant fibrous histiocytoma (MFH). The first study case was referred to us as a GCT of the tendon sheath. MFS has been uncommonly documented at nonacral sites, as the second case. [4],[5] Both cases were noted in patients aged 40 and 45 years that form the peak age for this tumor. [2]
Both cases displayed histopathological features of MFS, presence of which and lack of osteoclast-like giant cells, ruled out a GCT of the tendon sheath. Absent mitoses and tumor necrosis also ruled out an inflammatory MHF and an MFS-like pleomorphic sarcoma. Immunohistochemically, diffuse vimentin positivity in both cases, and CD34 and CD68 positivity in the former tumor, with SMA negativity, reinforced diagnosis of MFS and its fibroblastic lineage. [1],[2],[3] CD30 and CD15 negativity ruled out Hodgkin lymphoma, especially in the second tumor. Aforementioned features with SMA, desmin, and ALK1 negativity ruled out an inflammatory myofibroblastic tumor. Prominent inflammatory component, giant cells and lack of curvilinear vessels, despite pseudolipoblasts in the first tumor, ruled out a myxofibrosarcoma.
In view of eosinophils and intranuclear pseudoinclusions, initially, MFS was linked with a viral etiology. However, no such evidence was identified on IHC and molecular techniques. [1],[2] Lately, studies have disclosed a reciprocal translocation t (1; 10)(p22, q24) in an MFS and further, its morphologic and genetic "linkage" with hemosiderotic fibrolipomatous tumor (HFT). [6] We did not identify HFT-like areas, although focal hemosiderin pigment was noted in both tumors.
To conclude, diagnosis of MFS is vital, as it is under diagnosis as a benign lesion can lead to under treatment that could probably result in recurrences, whereas, an over diagnosis in form of MFH could result in radical treatments, instead of wide excision. Both the study cases were recommended follow-up, in view of unclear margins. Careful evaluation of clinicopathological features, and above all, an index of suspicion, can lead to a correct diagnosis of MFS.
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Bharat Rekhi
Department of Pathology, 8th Floor, Annex Building, Tata Memorial Hospital, Dr. E.B. Road, Parel, Mumbai - 400 012
Arundhati
Rekhi B
Desai SB
Jambhekar NA