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* Context.--The incidence, distribution, and significance of calcium pyrophosphate dihydrate deposition (CPPD) disease have not been extensively compared among various total joint resections. Objective.--To investigate and define the clinical and pathologic features of CPPD in hip, shoulder, and knee arthroplasties. Design.--We retrospectively reviewed consecutive total hip, knee, and shoulder arthroplasty cases (N = 3195) confirmed pathologically between January 1, 2017, and October 10, 2018, comparing clinical and pathologic data. Results.--Among 2004 hip arthroplasties, 61 (3%) had CPPD on pathologic examination; the majority had a histologic diagnosis of osteoarthritis, followed by fracture and avascular necrosis. Of 1113 knee arthroplasties, 98 (9%) had CPPD; all had a histologic diagnosis of osteoarthritis. Among 78 shoulder arthroplasties, 10 (13%) had CPPD; all but one had a histologic diagnosis of osteoarthritis. Patients with hip and knee CPPD were significantly older than those without CPPD. Of the 169 pathologically detected CPPD cases, only 35 (21%) were documented on preoperative radiologic images or by other clinical means; radiology reports were significantly more likely to document chondrocalcinosis in the knees than in the hips. Histologically, CPPD was noted almost exclusively in the separately submitted soft tissues/joint capsule, concomitantly involving the articular cartilage surface in only 3.0% (5 of 169) of cases. Conclusions.--Calcium pyrophosphate dihydrate deposition is more than twice as likely to occur in the knees and shoulders compared with the hips. Patients with CPPD in the knees or hips are usually not recognized preoperatively/radiologically and constitute a significantly older population. Reliably establishing the diagnosis of CPPD requires pathologic examination of the submitted soft tissue/joint capsule., Calcium pyrophosphate dihydrate deposition (CPPD) disease is a metabolic arthritis produced by the deposition of calcium pyrophosphate (CPP) dihydrate crystals in the synovium, joint capsule, and periarticular soft tissues, including [...]

* Context.--Bone and soft tissue tumors are heterogeneous, diagnostically challenging, and often defined by gene fusions. Objective.--To present our experience using a custom 34-gene targeted sequencing fusion panel. Design.--Total nucleic acid extracted from formalin-fixed, paraffin-embedded (FFPE) tumor specimens was subjected to open-ended, nested anchored multiplex polymerase chain reaction and enrichment of 34 gene targets, thus enabling detection of known and novel fusion partners. Results.--During a 12-month period, 147 patients were tested as part of routine clinical care. Tumor percentage ranged from 10% to 100% and turnaround time ranged from 3 to 15 (median, 7.9) days. The most common diagnostic groups were small round blue cell tumors, tumors of uncertain differentiation, fibroblastic/myofibroblastic tumors, and adipocytic tumors. In-frame fusion transcripts were identified in 64 of 142 cases sequenced (45%): in 62 cases, the detection of a disease-defining fusion confirmed the morphologic impression; in 2 cases, a germline TFG-GPR128 polymorphic fusion variant was detected. Several genes in the panel partnered with multiple fusion partners specific for different diagnoses, for example, EWSR1, NR4A3, FUS, NCOA2, and TFE3. Interesting examples are presented to highlight how fusion detection or lack thereof was instrumental in establishing accurate diagnoses. Novel fusion partners were detected for 2 cases of solid aneurysmal bone cysts (PTBP1-USP6, SLC38A2-USP6). Conclusions.--Multiplex detection of fusions in total nucleic acid purified from FFPE specimens facilitates diagnosis of bone and soft tissue tumors. This technology is particularly useful for morphologically challenging entities and in the absence of prior knowledge of fusion partners, and has the potential to discover novel fusion partners. (Arch Pathol Lab Med. 2021;145:851-863; doi: 10.5858/arpa.2020-0336-OA), Gene fusions occur frequently in bone and soft tissue (BST) neoplasms and, less frequently, in other kinds of solid tumors. (1-3) The observation of these fusions in patient specimens can [...]

The calcified chondroid mesenchymal neoplasm (CCMN) represents a recently recognized tumor type with only 50 well-documented cases in the English-language literature. Herein we report an additional case of CCMN presenting as a large mass in the temporomandibular joint region of a 41-year-old female. A review of previously reported cases and the current case of CCMN shows the following features: 1) average age 52 years (range 14–87 years) and an approximately even sex distribution; 2) most frequently involved sites: distal extremities (including foot, hand, wrist, forearm) (n=41) and temporomandibular joint/temporal/parotid region (n=9); 3) multilobular soft tissue tumor with chondroid to cartilaginous matrix, often grungy or lace-like calcifications, and variable cytologic atypia; 4) frequently detected FN1 rearrangement (n=15), including FN1 fusion with FGFR2 (n=7) or other receptor tyrosine kinases; 5) 2 reported local recurrences (after incomplete excision); 6) no reports of malignant biologic behavior. [ABSTRACT FROM AUTHOR]

Rosai-Dorfman disease (RDD) is a rare histiocytic proliferative disease of unknown etiology. Typically presenting with cervical adenopathy and constitutional symptoms, RDD involves bone in less than 10% of cases—and rarely presents as a primary intraosseous lesion. In this report, we describe the presentation of primary, bilateral intraosseous RDD, the first known case in the literature. Asymmetrically involving the lateral femoral condyles of a 59-year-old male, the lesion was discovered incidentally during evaluation and workup for giant cell tumor of bone involving the left tibia. Confirmation of the diagnosis required multiple biopsies and extensive evaluation—reflecting the diagnostic challenge associated with this case. We discuss the clinical, radiological, and pathological findings that allowed us to establish the diagnosis—as well as key differential diagnostic considerations and clinical outcome to date. [ABSTRACT FROM AUTHOR]

Abstract Introduction Chondrosarcoma is well-known to be primarily resistant to conventional radiation and chemotherapy. Case presentation We present the case of a 32-year-old Caucasian man with clear cell chondrosarcoma who presented with symptomatic recurrence in his pelvis and metastases to his skull and lungs. Our patient underwent systemic therapy with sunitinib and then consolidation with proton beam radiation to his symptomatic site. He achieved complete symptomatic relief with a significantly improved performance status and had an almost complete and durable metabolic response on fluorine-18-fluorodeoxyglucose positron emission tomography. Conclusions Our findings have important clinical implications and suggest novel clinical trials for this difficult to treat disease.

Objectives: To evaluate the necessity of pathologic examination for confirming the diagnosis of avascular necrosis (AVN).Methods: We retrospectively reviewed consecutive nonfractured total hip arthroplasty cases (n = 1,722), comparing operative diagnoses and radiologic data with final histologic diagnoses, focusing specifically on AVN.Results: Among 199 histologically confirmed cases of AVN, 62 (31%) had a preoperative diagnosis of osteoarthritis/degenerative joint disease (OA/DJD); 58 of the latter patients had radiology reports, but only two (3%) documented AVN. Patients with AVN preoperatively diagnosed as OA/DJD were significantly older (mean, 65 years) than patients with AVN correctly diagnosed clinically (mean, 52 years; P < .00001). Among 163 cases with a preoperative diagnosis of AVN, 26 (16%) were confirmed as OA/DJD; the radiology report incorrectly diagnosed AVN in 17 (65%) patients. These latter patients also were significantly older (mean, 60 years) than patients with AVN correctly diagnosed clinically (P = .0008). Patients with a preoperative clinical and/or radiologic diagnosis of AVN were more likely to be younger and have known AVN risk factors.Conclusions: Accurate and reliable diagnosis of AVN requires pathologic examination, especially among older patients without known risk factors. Prompt diagnosis may lead to behavioral changes in affected patients that reduce the risk of subsequent lesions. [ABSTRACT FROM AUTHOR]

Abstract Background Extremity liposarcomas can metastasize to different areas of the body but have rarely been demonstrated to metastasize to the liver. Due to the unusual occurrence of isolated metastatic extremity liposarcoma to the liver, the optimal treatment of this condition is unknown. Case presentation Less than one year after resection of a myxoid/round cell liposarcoma of the left lateral calf, a 61-year-old male presented with a CT scan showing a 2 cm low-density lesion in the right lobe of the liver. The lesion tripled in size over the next few months. An extensive evaluation revealed isolated disease to the liver. The lesion was surgically removed with a right hepatic lobectomy and the pathology was consistent with metastatic myxoid/round cell liposarcoma. Conclusion Although extremity liposarcoma rarely metastasizes solely to the liver, the best chance at cure is with complete resection. Unfortunately, cure rates are very low in the setting of metastatic disease. As expected, the patient experienced progression of disease at sites outside of the liver 5 months after the liver resection.