Mesenchymal chondrosarcomas (MC) are a rare and aggressive neoplasm characterized by primitive mesenchymal cells mixed with well differentiated islands of cartilage. MCs account for 2%-9% of all chondrosarcomas and typically metastasize to bones of the spine, ribs, or jaw with a ten-year survival rate of 27%. MC most commonly occurs in the second and third decades of life. Myxoid round cell liposarcomas (MRCL) are a form of liposarcoma neoplasm which occur in up to 30% of liposarcoma cases. Most MRCL cases occur between the second and third decade of life with a higher percentage of round cells associating with poorer prognosis. Surgical resection of MRCL is the most common treatment, with 14% of cases reoccurring following resection. A higher rate of recurrence is associated with a larger round cell component. 67% of recurrence cases of MRCL are associated with metastasis within 17 months. We report an unusual case of Mixed Mesenchymal Chondrosarcoma/Myxoid Round Cell Liposarcoma with later Recurrence as a Metastatic High-Grade Undifferentiated Round Cell Sarcoma and we review the literature.

Giant cell tumors of the bone (GCTB), while often benign, are regarded as locally aggressive and highly unpredictable with the capability to recur, metastasize, and even undergo sarcomatous transformation into a malignant variant. There have been inconsistent views regarding histomorphology, radiography and local occurrence of GCTB, and metastatic malignant GCTB. Herein, we describe the histological features of a case of GCTB with such atypical foci in which the initial diagnosis of malignancy was amended to a benign metastatic giant cell tumor. Whether the creation of a “borderline” or “atypical” GCTB category is necessary is yet to be determined.

Gastrointestinal stromal tumors (GISTs) are rare, making up less than 1% of all gastrointestinal tumors. Each year, approximately 4,000 to 6,000 adults in the United States will be diagnosed with a GIST. However, they are common mesenchymal tumors accounting for 80% of gastrointestinal mesenchymal tumors, as well as comprising 3-5% of all sarcomas and 1% of all gastrointestinal neoplasms. GISTs can occur along any location in the GI tract, but most GISTs are found in the stomach (60%), as well as the jejunum and ileum of the small intestine (20-30%). This case describes a 49-year-old male who presents with a malignant recurrent GIST two years after resection of a primary GIST. GISTs represent a problematic subset of gastrointestinal neoplasms due to the variability of immunohistochemistry and cytogenetics of the tumors across patients. GISTs should always be included in the differential diagnosis of presentation of a gastrointestinal mass. Early detection combined with complete resection of the mass, administration of tyrosine kinase inhibitors, as well as observation for possible recurrence is considered the current standard of care in patients with GIST.

Nocardiosis is a potentially lethal complication of organ transplantation. Each year, approximately 500 to 1000 cases of nocardiosis are diagnosed in the United States. Nocardiosis commonly occurs in the lung, brain, and heart of transplant recipients. This case describes a 63-year-old male who presents with a solitary brain and multiple pulmonary lesions. Nocardiosis represents a problematic diagnosis due to non-specific symptoms and imitation of more common differentials. Nocardiosis should always be included in the differential diagnosis of any patient who presents with brain, soft tissue, or cutaneous lesions and a concurrent or recent pulmonary lesion. Early detection combined with empiric antibiotic therapy is considered the current standard of care in patients with nocardiosis. We present a case of nocardiosis of the lung with hematogenous spread to the brain in post-transplant patient who responded well to treatment with complete recovery.

Myxoinflammatory fibroblastic soft tissue sarcomas are rare soft tissue sarcomas predominantly found in the upper extremities of middle-aged adults. Their rarity and diverse histological and anatomical presentations predispose to misdiagnosis oftentimes for more benign lesions such as ganglion cyst, giant cell tumor of the tendon sheath or tenosynovitis. This results in improper management in addition to delayed diagnosis placing patients at increased risk of worst-case scenarios including amputation, metastases or death. We are presenting the case of a 5-year-old female with myxoinflammatory fibroblastic soft tissue sarcoma of her hand initially misdiagnosed as a ganglion cyst, that recurred on two occasions after undergoing local excision. The reporting of this case aims to increase knowledge and awareness regarding the morphologic and immunohistochemical features of rare and often misdiagnosed myxoinflammatory fibroblastic soft tissue sarcomas. It is our hope that heightened awareness of this tumor will lead to inclusions as a differential diagnosis in soft tissue lesions of the extremities and thus avoid misdiagnosis and treatment.