[Joint tumors: rare but important differential diagnoses of malignant and benign tumors as well as pseudotumors in rheumatology]. / Gelenktumoren: Seltene, aber wichtige Differenzialdiagnosen von malignen und benignen Tumoren sowie Pseudotumoren in der Rheumatologie.

This review article elucidates the differential diagnostics of malignant and benign joint tumors, pseudotumors of the joints and the peri-implant tissue, which are rare but important entities in rheumatology and orthopedic rheumatology. The tissue of origin includes the synovium, peri-implant tissue, peri-articular fibrous tissue and peri-articular osseous tissue. Pseudotumors can be viewed as independent but heterogeneous entities. These are essentially manifested as tumor-like depositions of crystals, calcareous deposits, vascular malformations, ectasia of the synovia and joint capsule tissue and pseudocysts. Other causes for pseudotumors are focal destructive inflammation (e.g. induced by foreign bodies), high grade synovitis and focal fibrinoid necrosis (i.e. rheumatoid nodules). Methodologically, these diagnostics are based on conventional standard staining methods, immunohistochemical analyses of formalin-fixed and paraffin-embedded materials and on molecular diagnostic procedures. The latter are of great importance in cases of benign and malignant joint tumors. The most important immunohistochemical markers with respect to joint tumors are S100, SM-actin, CD68, CD34, STAT6, clusterin, Muc­4, beta-catenin and MDM2-FISH. The following markers are recommended for the differential diagnostics and typing of periarticular tumor metastases in the pathology of rheumatic diseases: AE1/AE3, CK8, p63, TTF­1, TGB, PSA, androgen receptor, GATA, CD56, chromogranin, CDX­2, SAT-B2, SALL4, estrogen and progesterone receptors, CD45LCA, CD30, CD79a and S100. Necrosis, inflammatory infiltrations and reparative inflammatory changes may complicate the histopathological classification. Therefore, a correlation with clinical, microbiological and radiological data in the sense of interdisciplinary synergistic diagnostics may be required.

Tenosynovial giant cell tumor: a case report.

BACKGROUND: This case reports the synchronous diagnosis of two rare unrelated diseases; leiomyosarcoma and tenosynovial giant cell tumor of the knee. It focuses on the challenges of diagnosing tenosynovial giant cell tumor, including cognitive biases in clinical medicine that delay diagnosis. It also demonstrates the pathogenic etiology of tenosynovial giant cell tumor, evidenced by the transient deterioration of the patients' knee symptoms following the administration of prophylactic granulocyte colony-stimulating factor given as part of the chemotherapeutic regime for leiomyosarcoma. CASE PRESENTATION: A 37-year-old Caucasian man presented with a left groin lump and left knee pain with swelling and locking. Investigations including positron emission tomography-computed tomography and biopsy revealed leiomyosarcoma in a lymph node likely related to the spermatic cord, with high-grade uptake in the left knee that was presumed to be the primary site. His knee symptoms temporarily worsened each time granulocyte colony-stimulating factor was administered with each cycle of chemotherapy for leiomyosarcoma to help combat myelosuppressive toxicity. Subsequent magnetic resonance imaging and biopsy of the knee confirmed a tenosynovial giant cell tumor. His knee symptoms relating to the tenosynovial giant cell tumor improved following the completion of his leiomyosarcoma treatment. CONCLUSIONS: Tenosynovial giant cell tumor remains a diagnostic challenge. We discuss the key clinical features and investigations that aid prompt diagnosis. The National Comprehensive Cancer Network clinical practice guidelines for soft tissue sarcoma have recently been updated to include the pharmacological management of tenosynovial giant cell tumor. Our case discussion provides an up-to-date review of the evidence for optimal management of patients with tenosynovial giant cell tumor, with a particular focus on novel pharmacological options that exploit underlying pathogenesis.

Trends in Tumor Site-Specific Survival of Bone Sarcomas from 1980 to 2018: A Surveillance, Epidemiology and End Results-Based Study.

OBJECTIVES: As diagnosis and treatment guidelines for bone sarcomas continue updating, it is important to examine whether, when, and which kinds of patients have had a survival improvement over the last four decades. METHODS: This cohort study included 9178 patients with primary bone and joint sarcomas from 1 January 1980 to 31 December 2018 using data from Surveillance, Epidemiology and End Results (SEER)-9 Registries. The follow-up period was extended to November 2020. Patients were divided by decade into four time periods: 1980-1989, 1990-1999, 2000-2009, and 2010-2018. The primary endpoint was bone sarcomas-specific mortality (CSM). The 5-year bone sarcomas-specific survival (CSS) rate was determined stratified by demographic, neoplastic, temporal, economic, and geographic categories. The associations between time periods and CSM were examined using a multivariable Cox regression model, with reported hazard ratio (HR) and 95% confidence interval (CI). RESULTS: The 5-year CSS rate for bone sarcomas was 58.7%, 69.9%, 71.0%, and 69.2%, in the 1980s, 1990s, 2000s, and 2010s, respectively. Older age, male gender, tumor sites at pelvic bones, sacrum, coccyx and associated joints, as well as vertebral column, osteosarcoma and Ewing tumor, and residence in non-metropolitan areas were independently associated with higher CSM risk. After adjusting for the covariates above, patients in the 1990s (HR = 0.74, 95% CI = 0.68-0.82), 2000s (HR = 0.71, 95% CI = 0.65-0.78), and 2010s (HR = 0.68, 95% CI = 0.62-0.76) had significantly lower CSM risks than patients in the 1980s. However, patients in the 2000s and 2010s did not have lower CSM risks than those in the 1990s (both p > 0.05). CONCLUSIONS: Although bone sarcomas survival has significantly improved since 1990, it almost halted over the next three decades. Bone sarcomas survival should improve over time, similar to common cancers. New diagnostic and therapeutic strategies such as emerging immune and targeted agents are warranted to overcome this survival stalemate.