Low-grade Spindle Cell Sarcoma Research Articles

Low-grade undifferentiated sarcoma with MEIS1::NCOA2-rearrangement primary to the lung: a case report

BackgroundMEIS1::NCOA2 is a rare fusion gene that has been recently described in a subset of spindle cell rhabdomyosarcomas and multiple low-grade undifferentiated spindle cell sarcomas predominantly arising in the genitourinary and gynecologic tracts with no specific line of differentiation. We present the first documented case of this neoplasm arising as a lung primary tumor.Case PresentationA 74-year-old woman with a 40-year smoking history presented with a 2.1 × 1.7 cm lung nodule discovered on computed tomography (CT) scan. A biopsy and subsequent lobe resection were performed, as well as an extensive metastatic work up, which revealed no additional masses. No specific line of differentiation was found by immunohistochemical staining, and an RNA-based fusion panel revealed a MEIS1::NCOA2 fusion, at which point a diagnosis of Low-Grade Undifferentiated Sarcoma with MEIS1::NCOA2-Rearrangement was rendered.ConclusionsThis report represents the first diagnosis of this tumor primary to the lung, and provides additional insight into the origin and localization of these rare tumors.

IgG4-Related Disease, a Systemic or Local Disease: This is the Problem

Background: Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory condition that forms tumefactive lesions in various organs, presenting with diverse clinical manifestations. Diagnosis of IgG4-RD could be challenging and relies on characteristic histopathological findings and elevated IgG4+ plasma cell counts. Case Presentation: The patient was a 48-year-old woman with diabetes mellitus initially presented with a painless breast mass. Imaging indicated irregular opacities and lymph nodes in the breast. Biopsy results revealed lymphoplasmacytic infiltration with IgG and IgG4 positivity, overall compatible with IG4-related disease. A mass resection was performed, and intraoperative assessment ruled out malignancy. Then, with a 5-month interval of no symptoms, the patient developed a cheek mass, initially misdiagnosed as low-grade spindle cell sarcoma. Subsequently, she underwent partial maxillectomy and further examination and histology confirmed IgG4-RD, meeting all diagnostic criteria. Conclusion: IgG4-RD is a rare, systemic fibroinflammatory condition with potential to mimic neoplastic processes. While IgG4 serum levels can be elevated, they are not a reliable diagnostic criterion. The two main features of IgG-related disease are an elevated number of IgG4-positive plasma cells within the tissue and a characteristic histopathological appearance including a dense lymphoplasmacytic infiltrate, storiform fibrosis, and obliterative phlebitis. Overall, diagnosis is based on the balance of clinical features, histopathology, and serum markers. This case underscores the diagnostic challenges posed by IgG4-RD, often mistaken for malignancies due to its invasive behavior and emphasizes the importance of considering IgG4-RD in differential diagnoses for tumor-like lesions, particularly when affecting multiple organs, to enable timely treatment decisions and prevent unnecessary interventions.

Low-grade Spindle Cell Sarcoma of the Tonsil: A Rare Entity

Background: Spindle cell sarcoma of the tonsil is an extremely rare malignancy in the head and neck region. The initial clinical presentation can be an asymptomatic mass lesion, and the biopsy of this growing mass should be conducted to exclude a malignant process. In this case report, we described a patient with spindle cell sarcoma of the tonsil with good clinical outcome after surgery alone. Case presentation: A 38-year-old male presented with foreign body sensation of the throat and clinical examination revealed asymmetrical enlargement of the right tonsil. Tonsillectomy was performed, and histopathological examination and immunohistochemistry analysis revealed a low-grade spindle cell sarcoma of the tonsil. He developed local recurrence at twelve months and underwent wide local excision. The patient remained well without any local recurrences and metastases eight years after diagnosis. Conclusion: We reported this case study in an effort to increase the awareness of spindle cell sarcoma of the tonsil and to emphasize the challenges in the diagnosis of this sarcoma. Surgical extirpation with a clear margin appeared to be an adequate treatment for the low-grade spindle cell sarcoma of the tonsil.

Biphenotypic Sinonasal Sarcoma: A Genetically Confirmed Case Showing Bone Invasion Accompanying a Non-neoplastic Respiratory Epithelium.

Biphenotypic sinonasal sarcoma is a newly established tumor entity that is associated with distinct clinicopathological findings. Biphenotypic sinonasal sarcoma is a rare, low-grade spindle cell sarcoma that arises in middle-aged females, exclusively in the sinonasal tract. A fusion gene involving PAX3 is detected in most biphenotypic sinonasal sarcomas, which aids in its diagnosis. Here, we report a case of biphenotypic sinonasal sarcoma with its cytological findings. The patient was a 73-year-old woman who presented with purulent nasal discharge and dull pain in the left cheek area. Computed tomography showed a mass extending from the left nasal cavity to the left ethmoid sinus, the left frontal sinus, and the frontal skull base. She underwent a combined transcranial and endoscopic approach for en bloc resection with a safety margin. Histologically, spindle-shaped tumor cells have been thought to proliferate mainly in the subepithelial stroma. Here, nasal mucosal epithelial hyperplasia was noted, and the tumor had invaded the bone tissue accompanying the epithelial cells. Fluorescence in situ hybridization (FISH) analysis showed a PAX3 rearrangement, and next-generation sequencing identified a PAX3::MAML3 fusion. Based on FISH, split signals were observed not in respiratory cells but in stromal cells. This indicated that respiratory cells were non-neoplastic. In the diagnosis of biphenotypic sinonasal sarcoma, the inverted growth of the respiratory epithelium can be a diagnostic pitfall. FISH analysis using a PAX3 break-apart probe is helpful not only for an accurate diagnosis but also for detecting the true neoplastic cells.

"Unusual Low-Grade Spindle Cell Sarcoma Pattern of Dedifferentiation Occurring in Chondrosarcoma: A Case Report"

"Unusual Low-Grade Spindle Cell Sarcoma Pattern of Dedifferentiation Occurring in Chondrosarcoma: A Case Report"

Recurrent MEIS1-NCOA2/1 fusions in a subset of low-grade spindle cell sarcomas frequently involving the genitourinary and gynecologic tracts.

Sarcomas with MEIS1-NCOA2 fusions have been so far reported in 2 cases each of primitive renal sarcomas and intraosseous pelvic rhabdomyosarcomas. Their histologic spectrum, anatomic distribution, and clinical behavior remain poorly defined. In this study, we report 6 additional spindle cell sarcomas with MEIS1-NCOA2 or NCOA1 fusions that fall into the same disease spectrum with the previously reported renal sarcomas. The patients' age range was wide (20-76 years, mean 46) and all except one were female. The tumors arose in the kidney (n = 2), and one each in the uterine corpus, vagina, scrotum, and para-rectal region. The consistent morphology was that of monomorphic spindle to ovoid cells in a storiform, whorling, or solid pattern. Alternating cellularity, myxoid stroma, and microcystic changes were seen in some cases. Mitotic activity varied greatly (<1-33/10 high power fields). The immunophenotype was nonspecific, with most cases expressing variable degrees of TLE1, WT1, cyclin D1, CD56, and CD10. Using various platforms of RNA-based targeted sequencing, MEIS1-NCOA2 fusions were recurrently identified in 5 cases, and a novel MEIS1-NCOA1 fusion was found in one renal tumor. The gene fusions were validated by fluorescence in situ hybridization using custom BAC probes. Of the 5 patients with available follow-up (5 months to 8 years), all experienced local recurrences, but no distant spread or death from disease. Our results expand the clinicopathologic spectrum of sarcomas with MEIS1-NCOA2/1 fusions, providing evidence of an undifferentiated spindle cell phenotype with nonspecific immunoprofile and low-grade clinical behavior.

Low-grade myofibroblastic sarcoma of the levator scapulae muscle: a case report and literature review

BackgroundLow-grade myofibroblastic sarcoma (LGMS) is described as a distinct atypical myofibroblastic tumor often with fibromatosis-like features and predilection for the head and neck, especially the oral cavity and larynx. LGMS arising in the levator scapulae muscle is extremely rare.Case presentationA 69-year-old woman was admitted to our hospital because she noticed a hard mass in her left neck six months prior. Magnetic resonance images (MRI) showed a soft tissue tumor of the left levator scapulae muscle. A core needle biopsy showed cellular fascicles or a storiform growth pattern of spindle-shaped tumor cells with minimally atypia. Immunohistochemistry revealed focally positive for α-smooth muscle actin (α-SMA), negative for S-100, and a low-grade spindle cell sarcoma was suspected. Following a biopsy, the tumor was resected with a wide surgical margin. Immunohistochemical staining was a positive for vimentin and α-SMA and negative for desmin, CD34, nuclear β-catenin, and h-caldesmon. LGMS diagnosis was determined based on the histopathological findings. The patient was alive with no evidence of disease eight years after the surgery.ConclusionsTo the best of our knowledge, this is the first case report of LGMS arising in the levator scapulae muscle. In addition to the case report, 48 reports with 103 LGMS cases are reviewed and discussed. In previous reports of LGMS, there were 43 females and 60 males, with a mean age of 43.0 years (range, 2–75). There were 13 (12.6%) patients aged < 18 years, 67 (65.1%) patients aged 18 to 59 years, and 23 (22.3%) patients aged ≥60 years. The average tumor size was 4.4 cm (range: 0.4–22.0). The commonest sites of LGMS was the tongue. Tumor growth patterns were evaluated in 52 cases, and 44 cases (84.6%) showed infiltrative growth patterns. Local recurrence was 26.7%, and distant metastasis was 4.4%. Because of the locally aggressive feature, it is important to diagnose LGMS with biopsy and to excise the tumor with an adequately wide margin.

Diagnostic Dilemma: Synovial Sarcoma Masked As Common Gynecological Pathologies

Study Objective Synovial sarcoma most commonly presents as a soft tissue tumor in young adults. This case report illustrates a diagnostic dilemma, in which a rare tumor was misdiagnosed on imaging on two separate occasions as common gynecological pathologies. Design N/A Setting N/A Patients or Participants N/A Interventions N/A Measurements and Main Results 45-year-old woman presented to the GynOncology clinic as a referral for management of a pedunculated leiomyoma identified on MRI. The patient was counseled on options, and agreed to placement of an intrauterine device. She re-presented two years later, and pelvic ultrasound showed that the previously identified fibroid was now believed to be a dermoid cyst; with interval increase in size, measuring 10.6 × 12.1 × 15. The patient underwent diagnostic laparoscopy, where a mass of indeterminate origin was noted; involving the round ligament, broad ligament, abdominal peritoneum, and abutting the dome of the bladder. Intraoperative frozen section returned indeterminate. Given the patient's desire for future fertility and uncertainty of malignancy, the decision was made to await final pathology before proceeding with surgical management. Pathology showed low-grade spindle-cell sarcoma with molecular features of synovial sarcoma. In two weeks time, the patient underwent a robotic-assisted total laparoscopic hysterectomy, bilateral salpingo-oophorectomy, and tumor debulking. Per the operative report, the mass that was first thought to be a pedunculated fibroid and then a dermoid cyst was an approximately 20cm retroperitoneal mass originating from the left broad ligament and occupying the entire left pelvic sidewall, pararectal space, paravesical space, and the space of Retzius and encasing the left ureter. Final pathology showed synovial sarcoma, which was confirmed with FISH results. Conclusion This case demonstrates synovial sarcoma misdiagnosed as common gynecological pathologies. This rare pathology is one that gynecologists should be aware of, as its early recognition and treatment allows for improved survival benefit with adjuvant chemotherapy.

Atypical lipomatous tumour/well-differentiated liposarcoma and de-differentiated liposarcoma in patients aged≤40years: a study of 116 patients.

Limited data exist on atypical lipomatous tumour (ALT)/well-differentiated liposarcoma (WDL) and de-differentiated liposarcoma (DDLPS) in children and young adults. Cases of ALT/WDL/DDLPS arising in patients aged≤40years were collected from multiple institutional and consultation archives. A total of 116 cases of ALT/WDL (75) and DDLPS (41) were identified, representing fewer than 5% of these tumours seen at our institutions during this time-period. The patients (59 male/57 female) ranged in age from 8 to 40years. Sites included deep central (abdomen/retroperitoneum/pelvis/groin) (n=60), extremity (n=42), trunk (n=5), head/neck (n=8) and mediastinum (n=1). De-differentiated patterns included: high-grade pleomorphic sarcoma, myxofibrosarcoma-like, heterologous rhabdomyoblastic differentiation, low-grade spindle cell sarcoma and homologous lipoblastic differentiation. Forty-one patients experienced a local recurrence and 11 patients with DDLPS developed metastasis. ALT arising in the extremities had lower recurrence rates than deep central WDL (5-year recurrence-free survival 88.9% versus 59.0%; P=0.002), while patients with deep central DDLPS experienced significantly more adverse events compared to WDL at this site (5-year event-free survival 11.9% versus 59.0%) (P<0.0001). Seven (of eight) head/neck tumours had follow-up available; five recurred, and one patient (DDLPS) with recurrence also experienced a metastasis. The single mediastinal tumour (DDLPS) recurred and metastasised. ALT/WDL and DDLPS occurring in patients aged≤40years is rare, but exhibits similar morphological features to its counterparts in older adults, including potential for heterologous and homologous de-differentiation in the latter. Although case numbers are limited, tumours arising in the head and neck exhibit high rates of adverse events, suggesting that classification as WDL rather than ALT is more appropriate.

New fusion sarcomas: histopathology and clinical significance of selected entities

Many sarcomas contain gene fusions that can be pathogenetic mechanisms and diagnostic markers. In this article we review selected fusion sarcomas and techniques for their detection. CIC-DUX4 fusion sarcoma is a round cell tumor now considered an entity separate from Ewing sarcoma with a more aggressive clinical course, occurrence in older age, and predilection to soft tissues. It is composed of larger cells than Ewing sarcoma and often has prominent necrosis. Nuclear DUX4 expression is a promising immuno histochemical marker. BCOR-CCNB3 fusion sarcoma is cyclin B3-positive, usually occurs in bone or soft tissue of children, and may mimic a poorly differentiated synovial sarcoma. EWSR1-NFATC2 sarcoma may present in bone or soft tissue. It is typically composed of small round cells in a trabecular pattern in a myxoid matrix resembling myoepithelioma. ACTB-GLI1 fusion sarcoma may mimic a skin adnexal carcinoma, showing focal expression of epithelial markers and S100 protein. NTRK-fusion sarcomas include, in addition to infantile fibrosarcoma with ETV6-NTRK3 fusion, LMNA-NTRK1 fusion sarcoma, a low-grade spindle cell sarcoma seen in peripheral soft tissues in children and young adults. Methods to detect gene fusions include next-generation sequencing panels, anchored multiplex polymerase chain reaction systems to detect partner for a known fusion gene, and comprehensive RNA sequencing to detect virtually all gene fusions. In situ hybridization testing using probes for both fusion partners can be used as an alternative confirmation technique, especially in the absence of satisfactory RNA yield. In addition, fusion protein-related and other immunohistochemical markers can have a high specificity for fusion sarcomas.

Fibrocartilaginous mesenchymoma of bone: a single-institution experience with molecular investigations and a review of the literature.

Fibrocartilaginous mesenchymoma is a rare intraosseous lesion, with a total of 26 cases described in the literature. This study describes the clinical, radiological and histological features of eight new cases of fibrocartilaginous mesenchymoma collected at a single institution between 1982 and 2016. The presence of GNAS and IDH1/2 mutations and MDM2 amplification was explored to evaluate possible links between fibrocartilaginous mesenchymoma, fibrous dysplasia, de-differentiated chondrosarcoma and low-grade osteosarcoma. Eight new cases of fibrocartilaginous mesenchymoma of bone identified in our archives, dating from 1982 to 2016, were reviewed. The diagnosis was not performed on the initial biopsy in any of these cases, due mainly to the absence of obvious cartilaginous differentiation. On imaging, the tumour contained cartilaginous calcifications and showed a very strong uptake of contrast medium after injection. Histologically, the tumour was characterized by spindle cell proliferation mimicking a low-grade spindle cell sarcoma, associated with epiphyseal growth-plate-like nodules of cartilage and bone production. Molecularly, no GNAS and IDH1/2 mutations or MDM2 amplification were found in the cases analysed. Only one case recurred 1 year following intralesional resection. None died of disease. This very rare bone tumour has a typical radiological and histological pattern and a favourable survival outcome after treatment. Local recurrences can be prevented with complete surgery. Fibrocartilaginous mesenchymoma does not seem to be related genetically to fibrous dysplasia, low-grade osteosarcoma and de-differentiated chondrosarcoma.

Kindle the Spindle: To Bring in Light a Rare Case of Eyelid Spindle Cell Sarcoma

Purpose: To bring in perspective a rare case of spindle-cell sarcoma of lid with intra-orbital metastasis. Methods: A seventy-five year old female presented with complaints of severe pain in right eye and right sided headache for 2 months along-with constant watering. She had a history of cataract surgery with IOL implantation in bag in right eye 4 months back. During the same time, a mass lesion was also removed from underside of right lower lid which was present for about 7-8 years. She was asthenic in built and was found to have pallor. On ophthalmic examination she was found to have Snellen’s visual acuity of 6/60 OD, 6/18 OS. Intra-ocular pressure was 37.5 mm of Hg OD, 18.6 mm of Hg OS. Ocular movements were restricted in lateral and superior gaze in right eye. On palpation stony hard, tender induration could be appreciated along the right infero-nasal lid margin. Fundus examination revealed chorio-retinal folds in inferior quadrant peripherally. No palpable lymph nodes were observed. CT scan brain and orbit was advised along-with routine blood investigations and IOP control medications. Results: CT scan revealed a heterogeneous cystic lesion measuring 17 × 16 × 21 mm in antero-inferior right orbit, abutting the globe and inferior rectus with thickening of uveo-scleral ring. The right globe was compressed and displaced supero-laterally. No bony erosion or infiltration of orbital fat or optic nerve was seen. Earlier histo-pathological report of excised lid tumor revealed low grade spindle cell sarcoma. Conclusion: Spindle cell sarcoma of lid is rare entity. This case report reveals a spindle cell sarcoma of lid with intraorbital metastasis.

Uterine Adenosarcoma.

Müllerian adenosarcoma is an uncommon biphasic tumor composed of malignant stromal and benign epithelial components. Morphologically, adenosarcoma is characterized by a broad leaflike architecture, reminiscent of phyllodes tumors of the breast. Periglandular cuffing of the stromal cells around the compressed or cystically dilated glands is characteristic. The mesenchymal component is typically a low-grade spindle cell sarcoma, whereas the epithelial counterpart is commonly endometrioid with frequent squamous or mucinous metaplasia and may, in some circumstances, show mild to moderate atypia. In all cases, it is important to assess for the presence of sarcomatous overgrowth and myometrial invasion, which are the prognostic factors. In this brief review, we present the clinical, histopathologic, and immunohistochemical features of adenosarcoma, as well as updates on the molecular biology of this neoplasm.

Comparative Pathology of Canine Soft Tissue Sarcomas: Possible Models of Human Non-rhabdomyosarcoma Soft Tissue Sarcomas

Comparative analyses of canine and human soft tissue sarcomas (STSs) are lacking. This study compared the histological and immunohistochemical (labelling for desmin, smooth muscle actin [SMA], CD31, pancytokeratin, S100 and CD34) appearance of 32 archived, formalin-fixed, paraffin wax-embedded canine STS tumour specimens by board-certified veterinary and medical pathologists, both blinded to the other's interpretations. Comparison between the veterinary and human diagnoses revealed a generally consistent pattern of interpretation with few notable variations. Most tumours (13/32) were judged to display similar histomorphological appearance to human low-grade spindle cell sarcomas, appearing non-distinctive and morphologically of a fibroblastic/myofibroblastic type. Five canine cases resembled human liposarcoma, but with atypical desmin-positive epithelioid cells present. Five canine cases resembled human spindle cell sarcoma with myxoid features and two additional cases resembled human myxofibrosarcoma. Seven canine cases were noted to resemble human undifferentiated sarcoma. Findings in the present study demonstrate that canine STSs display histological and immunohistochemical features similar to their human equivalents. Because of these cross-species similarities, a particular opportunity exists to understand the biology and treatment of human STS by potentially including dogs as clinical models.

Clinicopathologic characteristics of primary Schwannoma of the bone

To evaluate the diagnostic criteria and morphologic difference of primary schwannoma from that of soft tissue schwannoma. All neurogenic tumors of the bone in this hospital from 2002 to 2013 were reviewed, four cases of primary schwannoma arising from bone were selected. Their clinical features, radiologic appearance and pathologic findings were evaluated. Immunophenotyping was performed using EnVision method. All four cases had classic morphologic features and immunophenotype of conventional schwannoma. Compared with schwannoma of the soft tissue, primary bone schwannoma had the following features: benign radiological appearance, absence of capsule under light microscope, local infiltration of bone or destruction of bone cortex, occasionally involving extra-osseous soft tissue. Most tumors were solid, with less cystic degeneration. Histologically, the tumors were mainly composed of compact areas of spindle cells (Antoni A), and areas of hypercellularity could often be observed. Primary schwannoma of the bone is rare, usually arises within the long bones and flat bones. Compared to conventional soft tissue schwannoma, it shows different growth pattern, imaging and pathologic features; thus care should be exercised not to misdiagnose schwannoma of the bone as other primary low-grade malignant spindle cell sarcoma of the bone and to avoid unnecessary over-treatment.

Unclassified Low-Grade Spindle Cell Sarcoma of the Vulva

Unclassified Low-Grade Spindle Cell Sarcoma of the Vulva

Periosteal spindle cell hemangioma of the fibula: a case report

Spindle cell hemangioma is a rare benign tumor characterized by cavernous blood vessels and spindle cell proliferation. It typically arises in the subcutis of the distal extremities, particularly in the hand. Spindle cell hemangioma of periosteal origin is extremely rare, and our extensive literature search did not find any reports of this condition. We report here a case of spindle cell hemangioma of periosteal origin arising from the right fibula of a 49-year-old woman. Pathological examination of a needle biopsy specimen indicated the possibility of low-grade spindle cell sarcoma, and the patient underwent resection of the fibular diaphysis with a wide margin. Subsequent examination of the surgical specimen revealed a diagnosis of periosteal spindle cell hemangioma. Follow-up examination at 10 months showed no evidence of local recurrence or metastasis. A large tissue sample was required for definitive diagnosis in this case. Spindle cell hemangioma behaves in a benign fashion, but recurrence occurs in about 60% of cases. Excision of the fibula was a reasonable course of management in this case because these patients usually maintain good function. Reports of additional cases will be required to determine the most appropriate treatment for this tumor.

Myofibroblastoma Breast with Unusual Morphological Features. Cytohistopathogical Diagnostic Pitfalls and Role of Immunohistochemistry-Review of Literature

Myofibroblastoma (MFB) is a rare mesenchymal tumour, derived from mammary stromal fibro-myofibroblasts, with diverse biological and morphological behaviour. Large and cellular myofibroblastomas, especially those with epitheliod like cells, can mimic various spindle cell lesions and metaplastic carcinomas, thus posing diagnostic challenge. A 50-year woman presented with slow growing, painless lump in the left breast. Fine Needle Aspiration (FNA) smears showed predominant atypical spindle cell population, pleomorphic epithelial like cells and giant cells. Cytodiagnosis of atypical spindle cell lesion with the possibility of metaplastic carcinoma was suggested. Histopathological examination showed fascicles of spindle cell population admixed with epithelial like cells, atypical cells and tumour giant cells, thus raising differential diagnosis of metaplastic carcinoma, low grade spindle cell sarcoma and myofibroblastic tumour. Lymph nodes were negative for metastatic deposits. Immunohistochemistry revealed variable coexpression of markers for vimentin, fibronectin, CD34, SMA (smooth muscle actin), but negative expression for , S-100, CD99, CK7 (cytokeratin 7), HMWK (high molecular weight keratin), ER (oestrogen receptor) and PR(progesterone receptors). Diagnosis of cellular myofibroblastoma with mixed unusual morphological features was defined, based on both histological and immunohistochemical features. MFB may cause a potential diagnostic pitfall while interpreting FNA and histopathological sections due to its wide differential diagnosis. The distinction of MFB from its cytohistological mimics of malignancy is crucial to avoid unnecessary extensive procedures. The case report emphasizes the role of immunohistochemistry as gold standard in diagnosis of MFB. The case is also being presented because of its large size and rare mixed unusual morphological features.

Nodular fasciitis of the hand in a young athlete. A case report

Nodular fasciitis is a rapidly growing mass, with high cellularity and mitotic activity, that can be both clinically and histologically misdiagnosed as a soft tissue sarcoma. Nodular fasciitis of the hand is an extremely rare condition. We report a 17-year-old male hand-ball player with nodular fasciitis in the dominant hand. The patient presented with a rapidly growing mass in his right hand and no history of major trauma. On physical examination, a painful mass measuring 2 cm in diameter was observed in the first web space. Magnetic resonance imaging (MRI) demonstrated a subcutaneous mass with isointensity on T1-weighted images and inhomogeneous high intensity on T2-weighted images. The lesion was inhomogeneously enhanced after intravenous administration of gadolinium. Moreover, thallium-201 scintigraphy showed high uptake at the early phase and no wash-out at the delayed phase. We performed an excisional biopsy. The mass was present subcutaneously and adhered to the interosseous muscle fascia. Although a pathological examination by frozen section during surgery showed a low-grade spindle cell sarcoma, the final histological diagnosis was nodular fasciitis. There was no evidence of local recurrence at the recent follow-up 2 years after the operation. We speculate that repeated small injuries as a result of sports activities played an important causative role in the nodular fasciitis.

A rare case of low-grade myofibroblastic sarcoma of the femur in a 38-year-old woman: a case report

IntroductionPrimary myofibroblastic sarcoma of the bone is a rare spindle cell tumour with, to the best of our knowledge, only eight cases reported in the available English language literature. The disease's rarity and its low-grade features make an accurate diagnosis difficult in most cases. The differential diagnoses of this unusual tumour include various benign entities as well as other sarcomas. Due to the difference in prognosis, a precise pathologic diagnosis is essential, which requires a combination of thorough morphologic examination, immunohistochemistry and electron microscopy wherever available.Case presentationWe report the case of a 38-year-old Indian woman with a lytic lesion in her left femur. The tumour was associated with cortical destruction and soft tissue extension. A biopsy from the soft tissue component showed features suggestive of a low-grade malignant mesenchymal tumour. Excision of the tumour was performed and histopathological examination showed a low-grade spindle cell sarcoma with collagenous stroma. Expressions of vimentin and smooth muscle actin were also noted. Ultrastructural examination confirmed its myofibroblastic nature. A final diagnosis of low-grade myofibroblastic sarcoma of the left femur was thus rendered.ConclusionLow-grade myofibroblastic sarcoma is one of the rarer osseous spindle cell sarcomas depicting a favourable prognosis in the cases reported so far. Its diagnosis requires ancillary techniques like immunohistochemistry and electron microscopy. To the best of our knowledge, we report the ninth case in the literature and the first case from our subcontinent.