Differential metabolic secretion between mdx mouse-derived spindle cell sarcomas and rhabdomyosarcomas drives tumor type development

The dystrophin (DMD) gene is recognized for its significance in Duchenne muscular dystrophy (DMD), a lethal and progressive skeletal muscle disease. Some DMD patients, as well as model mice with muscular dystrophy (mdx), spontaneously develop various types of tumors, among which rhabdomyosarcoma (RMS) is the most prominent. By contrast, spindle cell sarcoma (SCS) has rarely been reported in patients or mdx mice. In this study, we aimed to use metabolomics to better understand the rarity of SCS development in mdx mice. Gas chromatography-mass spectrometry was employed to compare the metabolic profiles of spontaneously developed SCS and RMS tumors from mdx mice, and metabolite supplementation assays and silencing experiments were used to assess the effects of metabolic differences in SCS tumor-derived cells. The levels of 75 metabolites exhibited differences between RMS and SCS, 25 of which were significantly altered. Further characterization revealed downregulation of non-essential amino acids, including alanine, in SCS tumors. Alanine supplementation enhanced the growth, epithelial-mesenchymal transition, and invasion of SCS cells. Reduction of intracellular alanine via knockdown of the alanine transporter Slc1a5 reduced the growth of SCS cells. Lower metabolite secretion and reduced proliferation of SCS tumors may explain the lower detection rate of SCS in mdx mice. Targeting of alanine depletion pathways may have potential as a novel treatment strategy.

Spindle Cell Carcinoma Presenting as a Massive Pleural Effusion

The lung's sarcomatoid carcinomas (SC) are a heterogeneous sporadic group of non-small cell lung carcinomas (NSCLCs) and are very challenging to diagnose and treat. Spindle cell carcinoma (SpCC) is a very rare subset of this group. Hence, the prognosis and treatments are unclear due to the limited literature available. The presentation of this cancer varies based on the site of the neoplasm and the complications and metastases observed at the time of diagnosis. Here, we report a 73-year-old man who presented to the emergency room after two months of worsening dyspnea and fatigue. Chest X-ray showed an extensive left-sided pleural effusion. A computed tomography (CT) scan of the chest showed a pleural-based mass that came back as SpCC, for which he was referred to a university hospital.

A Rare Case of Spindle Cell Sarcoma With Rare Asymptomatic Cerebellar Metastasis

Sarcomas are one of the rarest cancers, occurring in less than 1% of all adult malignancies. Spindle cell sarcomas are one subset of soft tissue sarcomas that are even less commonly reported in the literature due to the scarcity of cases, especially with the presence of brain metastases. We present a case of an adult male who presented with non-specific exertional dyspnea and chest pain, which was found to have spindle cell sarcoma with cerebellar metastasis.

EWSR1::POU2AF3(COLCA2) Sarcoma: An Aggressive, Polyphenotypic Sarcoma With a Head and Neck Predilection

EWSR1::POU2AF3 (COLCA2) sarcomas are a recently identified group of undifferentiated round/spindle cell neoplasms with a predilection for the head and neck region. Herein, we report our experience with 8 cases, occurring in 5 men and 3 women (age range, 37-74 years; median, 60 years). Tumors involved the head/neck (4 cases), and one each the thigh, thoracic wall, fibula, and lung. Seven patients received multimodal therapy; 1 patient was treated only with surgery. Clinical follow-up (8 patients; range, 4-122 months; median, 32 months) showed 5 patients with metastases (often multifocal, with a latency ranging from 7 to 119 months), and 3 of them also with local recurrence. The median local recurrence-free and metastasis-free survival rates were 24 months and 29 months, respectively. Of the 8 patients, 1 died of an unknown cause, 4 were alive with metastatic disease, 1 was alive with unresectable local disease, and 2 were without disease. The tumors were composed of 2 morphologic subgroups: (1) relatively bland tumors consisting of spindled to stellate cells with varying cellularity and fibromyxoid stroma (2 cases) and (2) overtly malignant tumors composed of nests of "neuroendocrine-appearing" round cells surrounded by spindled cells (6 cases). Individual cases in the second group showed glandular, osteogenic, or rhabdomyoblastic differentiation. Immunohistochemical results included CD56 (4/4 cases), GFAP (5/8), SATB2 (4/6), keratin (AE1/AE3) (5/8), and S100 protein (4/7). RNA sequencing identified EWSR1::POU2AF3 gene fusion in all cases. EWSR1 gene rearrangement was confirmed by fluorescence in situ hybridization in 5 cases. Our findings confirm the head/neck predilection and aggressive clinical behavior of EWSR1::POU2AF3 sarcomas and widen the morphologic spectrum of these rare lesions to include relatively bland spindle cell tumors and tumors with divergent differentiation.

Malignant Solitary Fibrous Tumor of the Inguinal Region: A Case Report

A solitary fibrous tumor (SFT) is a rare spindle cell neoplasm in adults, usually found in the pleural and thoracic cavities. We report an interesting case of a malignant solitary fibrous tumor in a 64-year-old male who presented with a history of swelling in his right inguinal region that gradually increased in size during the past three years. Computed tomography (CT) and magnetic resonance imaging (MRI) scans of the abdomen and pelvis showed a rounded solid mass originating from the right inguinal canal suggestive of sarcoma. Elective excision of the mass was done under general anesthesia with histopathology confirming the diagnosis of high-grade spindle cell sarcoma in keeping with a malignant solitary fibrous tumor. Postoperatively, the patient had no complications and was discharged on postoperative day 4. The patient was then treated with radiotherapy. He remained free of recurrence for two years postoperatively.

Case report: Squamous cell carcinoma and spindle cell sarcoma (SCS) arising in a mature cystic teratoma of the ovary

Objective

Malignant transformation of mature ovarian teratoma is a rare phenomenon, mainly occurring in postmenopausal period. Squamous cell carcinoma accounts for 80% of all malignant transformations. Sarcoma transformation is much less common and tends to imply a poorer prognosis and aggressiveness.

Case report

We report a case of undifferentiated sarcoma with squamous cell carcinoma in a mature cystic teratoma of the ovary in a 36-year-old woman. The tumor shows epithelial and stromal components. This is a unique report of a benign teratoma of the ovary with malignant transformation, showing epithelial and sarcomatous components. This young woman presented with abdominal distension and a rapidly enlarging ovario-derived pelvic mass with a slightly elevated CA199 tumor marker of 115.9 U/ml. The woman underwent transabdominal excision of the left ovarian cyst on October 20, 2020. During the operation, rapid freezing pathological examination did not indicate malignancy. The postoperative paraffin pathology revealed undifferentiated sarcoma with squamous cell carcinoma (from mature cystic teratoma malignancy), and she finally received comprehensive staging surgery. Postoperative paraffin pathology showed no residual cancer in uterus and other tissues, and all lymph nodes were negative. The patient was finally diagnosed with ovarian malignant tumor IC1 stage (high-grade spindle cell sarcoma complicated with squamous cell carcinoma). Chemotherapy was completed three times after surgery, and no signs of recurrence were found after follow-up.

Conclusion

The preoperative diagnosis and intraoperative rapid freezing examination of malignant transformation of mature teratoma of ovary are challenging.

Spindle Cell Sarcoma of the Uterus Harboring MEIS1::NCOA1 Fusion Gene and Mimicking Endometrial Stromal Sarcoma

MEIS1::NCOA1/2 sarcomas are a newly recognized group of exceedingly rare low-grade spindle cell sarcomas that often involve the genitourinary and gynecologic tracts. Due to its deceptively low-grade morphology and the non-specific immunoprofile, these neoplasms may pose a diagnostic challenge by histologically mimicking other entities such as endometrial stromal sarcoma, smooth muscle tumor, or uterine perivascular epithelioid cell tumor (PEComa). Histologically, MEIS1::NCOA1/2 sarcomas typically show spindle cell proliferation with hyperchromatic nuclei and a generalized cytologic uniformity, arranged in short fascicles and exhibiting alternating zones of hypo- and hypercellularity. Among the previously reported cases, molecular analysis revealed the MEIS1::NCOA2 fusion as the most commonly detected fusion gene, whereas the MEIS1::NCOA1 fusion gene has been reported in only a single case that involved kidney. Herein we report the first case of uterine sarcoma harboring the MEIS1::NCOA1 fusion gene that was initially misclassified as low-grade endometrial stromal sarcoma, demonstrating its clinicopathologic features, and highlighting the essential role of molecular pathology to arrive at the accurate diagnosis that may alter disease classification and inform therapy.

Difficulty in Diagnosing Rare Cardiac Tumors: A Case Series

Primary cardiac tumors are rare because metastatic lesions from distant sites account for most masses. We are reporting two cases of malignant intracardiac masses with their diagnostic dilemma. Our first patient is a 72-year-old male with a pertinent history of desmoplastic and spindle cell melanoma who presented after his surveillance positron emission tomography (PET) scan showed a hypermetabolic lesion in the inferior pericardium. The initial impression for this mass is recurrent malignant melanoma. After an initial negative endometrial biopsy, the patient underwent debulking surgery, and pathology revealed high-grade spindle cell sarcoma. The patient underwent chemotherapy but had a disease progression and ultimately elected hospice care. Our second patient is a 75-year-old male with a history of stage IB adenocarcinoma of the lung who presented with progressive dyspnea. An echocardiogram revealed a moderate-sized left ventricular mass. Initial assessment based on tumor morphology and location suggested possible cardiac sarcoma. However, the patient's subsequent cardiac biopsy revealed small cell carcinoma, likely of primary cardiac origin, as no other primary nidus of the tumor was seen. Based on this result, the patient has been started on carboplatin, etoposide, and atezolizumab and responded well as of the writing of this manuscript. Given the rarity of malignant primary cardiac tumors and their variable clinical presentation, intracardiac masses are often diagnosed incidentally. In addition, given the high risk of biopsy for intracardiac masses, a presumptive diagnosis is rendered via imaging techniques. However, most of these tumors have no pathognomonic imaging findings, and their diagnosis relies heavily on physician interpretation and experience. Our case series illustrated the unpredictable nature of noninvasive methods and that even endometrial biopsy can return a false negative. Therefore, it is essential to be persistent in obtaining a pathological diagnosis, especially if the clinical picture is unclear. While these more invasive methods present the challenge of identifying whether the procedure is truly needed and locating a skilled operator, it could change the diagnosis entirely and open the patient up to new therapies.

Spindle cell sarcoma with KIAA1549-BRAF resembling infantile fibrosarcoma morphologically: A case report and literature review

Infantile fibrosarcoma (IFS) commonly harbors ETS variant transcription factor 6 (ETV6)-neurotrophic receptor tyrosine kinase 3 (NTRK3) fusion. However, the recent accessibility to clinical next-generation sequencing (NGS) has revealed ETV6-NTRK3 negative spindle cell sarcomas resembling IFS morphologically, involving NTRK1/2, MET, RET and BRAF. The present report describes a pediatric case of spindle cell sarcoma with KIAA1549-BRAF resembling IFS morphologically. A 20-month-old female patient was referred to Kobe Children's Hospital (Kobe, Japan) for the treatment of intrathoracic spindle cell sarcoma. Pathologically, the intrathoracic tumor cells were composed of spindle cells with focal hemagiopericytomatous pattern. In immunohistochemistry analysis, the intrathoracic tumor cells focally expressed desmin and WT-1 and were negative for pan-tropomyosin receptor kinase (TRK), S-100 and CD34. Fluorescence in situ hybridization analysis for ETV6 and capicua transcriptional repressor revealed negative split signals. Although the patient was initially diagnosed with IFS morphologically, KIAA1549-BRAF fusion transcript was detected by comprehensive genomic profiling with NGS using intrathoracic tumor tissues and confirmed by reverse transcription-PCR. Chemotherapy induced a reduction in the tumor size. At present, the patient is alive with the disease and has been receiving therapy for 8 months since the initiation of chemotherapy. Review of BRAF-altered spindle cell sarcomas resembling IFS morphologically revealed the inconsistency in immunohistochemical expression patterns and the diversity of BRAF fusion genes and mutations. Therefore, the elucidation of genomic profiling by NGS may assist in making an appropriate diagnosis and selecting novel alternative therapies in ETV6-NTRK3-negative spindle cell sarcomas resembling IFS morphologically.

Primary Spindle Cell Sarcoma of the Lung with Fusion: An Extremely Rare Case of a Potentially Emerging Entity and Review of the Literature

Originally described in a rare subset of poorly differentiated squamous cell carcinomas termed NUT carcinomas, NUTM1 rearrangements are now known to characterize a wide spectrum of neoplasms including sarcomas, poromas/porocarcinomas, unclassified adnexal carcinomas and pediatric acute lymphoblastic leukemia. The advent of next-generation sequencing (NGS) has led to the identification of a multitude of novel fusion partners in addition to BRD4, which was initially reported in the majority of NUT carcinomas. NUTM1-rearranged sarcomas usually harbor fusions with the MAD gene family (MXD1, MXD4, MGA) and present as spindle cell proliferations in diverse locations in patients of all ages. Herein, we present a very rare case of spindle cell sarcoma of the lung, which harbored a NUTM1::MGA fusion and offer a comprehensive update of the recent data.

Novel MAP4::RAF1 Fusion in a Primary Bone Sarcoma: Expanding the spectrum of RAF1 Fusion Sarcoma

Soft tissue tumors with RAF1 fusion had been emerging as a group of tumors with peculiar histology and immunoprofile. While a case series and rare case reports of RAF1 translocated sarcoma had been reported, to our knowledge a primary bone tumor with RAF1 translocation and fusion partner with MAP4 had not been described in the literature. The patient was a 60-year-old lady, with strong family history of breast cancer, who presented with pathological fracture of right humerus. X-ray revealed a 9.7 cm juxta-articular lesion of the proximal humerus, which was expansile and lytic with a non-sclerotic well defined border distally, radiologically suggestive of a giant cell tumor of bone. Excision was performed after initial biopsy. Histology showed a monomorphic low grade spindle cell lesion with prominent hyalinized stroma. Immunohistochemistry demonstrated diffuse CD34 staining, with focal staining for S100. Gene sequencing for histone 3 H3 genes was negative for hotspot mutation. Targeted RNA-seq sequencing revealed the presence of MAP4::RAF1 fusion, which was confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) and fluorescence in-situ hybridization (FISH) break-apart probes involving both genes. The overall features were consistent with a primary bone sarcoma with RAF1 fusion. This report expanded the spectrum of RAF1 fusion sarcoma and was the first report documenting its primary occurrence in bone.

Primary Malignant Peripheral Nerve Sheath Tumors of Bone: A Clinicopathologic Reappraisal of 8 Cases

Primary spindle cell and pleomorphic sarcomas of bone represent an exceedingly rare group of mesenchymal malignancies that include "soft tissue" histotypes, as malignant peripheral nerve sheath tumour. Outside the head and neck region, only 36 cases of primary malignant peripheral nerve sheath tumour of bone have been described. We retrieved from our archives eight cases of primary malignant peripheral nerve sheath tumour of bone arising outside the head and neck region, describing their clinical, radiological, and morphologic features. Our series, in which all but one patient died of diseases after a median of seven months, confirms that primary malignant peripheral nerve sheath tumours of bone are aggressive tumours. Pathologists should be aware of this rare histotype. More aggressive and active adjuvant treatments should be investigated.

A Large Benign Solitary Fibrous Tumor in the Pelvis: A Unique Group

Solitary fibrous tumors (SFTs) are a rare type of sarcoma and ubiquitous in nature, occurring anywhere in the body. Although only a few hundred cases have been described so far, certain histological features, such as hypercellularity and high mitotic index, have been associated with a more malignant course. Tumor sizes larger than 10 cm have also been associated with higher recurrence rates. There are clinical recommendations for two distinct patient groups, those with small and benign SFTs or those with large and malignant SFTs. There are few that acknowledge the unique group of those with large but benign tumors. A case involving a 62-year-old man who underwent surgical resection of a large but benign solitary fibrous tumor of the pelvis is described.

Spindle cell sarcoma: a rare cause of a spontaneous pneumothorax

Secondary spontaneous pneumothoraces are associated with a variety of lung disorders. Malignancy is a rare cause of a pneumothorax and rarely the presenting feature. Cavitating primary tumours are less frequent causes of pneumothoraces than secondary tumours. We present the case of an asymptomatic spontaneous pneumothorax in a 71-year-old never-smoking woman. Her right apical pneumothorax was diagnosed by chance on a chest radiograph for a fall. Her final diagnosis was a primary spindle cell sarcoma of the pleura. This case demonstrates the need to explore the underlying causes of a non-resolving pneumothorax. The early diagnosis of her sarcoma allowed curative treatment.

Beyond the Diagnosis of Group IV Pulmonary Hypertension: Chronic Thromboembolic Pulmonary Hypertension Mimickers

We present 3 patients with similar clinical presentation of group IV pulmonary hypertension but with totally different diagnoses. This case series highlights the need to keep a broad differential diagnosis and to utilize more diverse imaging modalities for the diagnosis of group IV pulmonary hypertension. (Level of Difficulty: Beginner.).

EWSR1-SMAD3-Positive Fibroblastic Tumor

EWSR1-SMAD3-positive fibroblastic tumor is a recently characterized neoplasm with distinct clinicopathologic features and recurrent EWSR1-SMAD3 gene fusion. ESFT typically presents as a small, painless tumor in extremity subcutaneous tissues. Their behavior is benign, although they are prone to local recurrence. They typically comprise two components: intersecting fascicles of overlapping, uniform plump spindle cells, and less cellular hyalinized areas containing stippled calcifications. Immunohistochemically, the cells consistently show diffuse ERG nuclear expression, while other markers are negative. The morphology of this neoplasm can lead to histologic confusion with both benign and malignant soft tissue tumors, including monophasic synovial sarcoma, malignant peripheral nerve sheath tumor, and spindle cell sarcoma, not otherwise specified. Correct identification of ESFT is critical, most importantly to avoid unnecessary overtreatment as sarcoma.

Solitary fibrous tumor in the subcutaneous soft tissues of the left abdominal wall: A case report

Solitary fibrous tumor (SFT) derived from the abdominal wall is rare. We report a case of SFT in the abdominal wall. When abdominal computed tomography reveals soft-tissue mass and analysis of preoperative needle biopsy reveals spindle cell tumor, the possibility of SFT should be considered.

Biological implant-associated granulomatous inflammation resulting in secondary hypercalcemia and azotemia in a dog

Implant associated granulomatous inflammation causing hypercalcemia can occur following use of commercial xenogeneic pericardial tissue patches in dogs. Removal of the implant can result in resolution of the hypercalcemia, suggesting a causal relationship between the tissue reaction to a xenogeneic implant and development of hypercalcemia.

Unusual case of spindle cell sarcoma metastases to right ventricle: a case report and a literature review

Cardiac metastases from sarcoma are uncommon. Due to their rarity there is not a standard of care. However, complete cardiac metastases resection is the best option but most of patients has widespread disease. In these patients palliative radiotherapy (RT) might improve symptoms and prevent further cardiac function decline. Here we present the case of a symptomatic 30-year-old woman with spindle cell sarcoma metastasis of right ventriculum and widespread disease. The patient received radiotherapy to the heart with palliative intent. Cardiac metastases represent a challenging clinic problem. Treatment should be individualized in a multidisciplinary setting, when possible surgery seems to be the best options. However, radiotherapy even in case of widespread disease can improve clinical control symptoms by reducing the mass effect.

Spindle cell sarcoma of pulmonary artery mimicking thromboembolism with lung metastasis detected in fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography

Pulmonary artery sarcoma (PAS), although rare, must be considered in the differential diagnosis of pulmonary thromboembolism (PTE). This tumor is highly malignant and the prognosis is very poor. As much as the standardized uptake values (SUVs) at fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET) have helped in differentiating between benign and malignant tumors, visualization of a low-attenuation filling defect within a pulmonary artery on contrast-enhanced chest computed tomography (CT) can be suggestive of a malignancy, such as PAS, if the lesion shows high FDG uptake at PET. We present a case of PAS that showed high FDG uptake on integrated FDG PET/CT and with lung metastasis. Patient underwent endoscopic bronchial ultrasound-transbronchial needle aspiration (EBUS-TBNA), which confirmed spindle cell sarcoma.

Transthoracic echocardiographic assessment of spindle cell sarcoma of the pulmonary artery in a child

In this report, we present a case of spindle cell sarcoma of the pulmonary artery diagnosed by transthoracic echocardiography. To the best of our knowledge, this case is the youngest reported case of pulmonary artery sarcoma (PAS) to date. PAS is frequently confused for pulmonary embolism; in this case, echocardiographic findings allowed for differentiation between pulmonary embolism and solid tumor.