Chondrosarcoma arising within synovial chondromatosis of the lumbar spine

Synovial chondromatosis: Rare involvement of metacarpophalangeal joint and diagnostic challenges in MR imaging

Synovial chondromatosis (SC) is a rare benign tumor of the cartilaginous tissue that frequently affects large joints intra-articularly. Characteristic imaging findings were reported for the diagnosis of SC. Herein, we report a case of SC of the metacarpophalangeal joint with atypical MRI findings. Considering the clinical presentation, erosion, absence of calcification on X-ray and CT, and low intensity on short tau inversion recovery (STIR), tenosynovial giant cell tumor was the initially diagnosis. However, histopathological findings revealed SC with fibrosis, which was confirmed using Elastica Van Gieson (EVG) staining. In general, low intensity on STIR in SC indicate calcification; however, it can also represent fibrosis in SC. In this case, the diagnosis of SC using MRI was limited highlighting the importance of histopathological findings for an accurate diagnosis of SC.

Primäre synoviale Chondromatose

Hintergrund

Die primäre synoviale Chondromatose (SC) ist eine seltene Erkrankung der Synovialmembran unklarer Ätiologie. Der aktuelle Wissensstand zu dieser Erkrankung soll in einer kurzen Übersicht dargestellt werden.

Methoden

Übersichtsarbeiten und rezente Fallberichte zur SC wurden systematisch ausgewertet und mit Daten eigener Fälle in Kontext gesetzt.

Ergebnisse

Auf Grund neuer genomischer Daten wird die SC als benigne Neoplasie eingestuft. In 60 % der Fälle liegen Mutationen im Fibronektin-1-Gen (FN1) und/oder im Gen für den Activin-A-Typ-II-Rezeptor (ACVR2A) vor. Diagnoseweisend ist die Magnetresonanztomographie (MRT) und die meist arthroskopische Biopsie der Synovia. An einem Fallbeispiel soll gezeigt werden, dass die Knorpelaggregate der SC radiologisch nicht immer schattengebend sein müssen. Differenzialdiagnostisch kommen Monarthritiden anderer Ursachen, andere Gelenk- und Muskelerkrankungen mit Mineralisierung sowie weitere von der Synovialmembran ausgehende Erkrankungen in Betracht. Die Entartungsrate liegt bei 2–4 %. Therapeutisch hat sich in den letzten Jahren das arthroskopische Vorgehen durchgesetzt, das an die Ausdehnung der Erkrankung adaptiert wird.

Schlussfolgerung

Genomische Untersuchungen sowie Fallserien und Fallberichte aus jüngerer Zeit werfen ein neues Licht auf die SC. Therapeutisch wird in jüngeren Arbeiten überwiegend arthroskopisch vorgegangen.

[Joint tumors: rare but important differential diagnoses of malignant and benign tumors as well as pseudotumors in rheumatology]

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, Muc‑4, 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, TTF‑1, TGB, PSA, androgen receptor, GATA, CD56, chromogranin, CDX‑2, 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.

Synovial chondrosarcoma: a single-institution experience with molecular investigations and review of the literature

AIMS

To evaluate the available diagnostic histological criteria for synovial chondrosarcoma and to screen for the presence of IDH1/IDH2 mutations in a series of cases of this malignant cartilaginous neoplasm.

METHODS AND RESULTS

Ten cases of synovial chondrosarcoma diagnosed at our institute were reviewed. At presentation, all tumours occurred in adults (median age, 62 years). The most common location was the knee joint (five cases), and the size at diagnosis ranged from 30 mm to 170 mm. Eight patients had secondary synovial chondrosarcomas associated with pre-existing/recurrent or concomitant synovial chondromatosis. Five patients had local recurrences and three had lung metastases. All patients with intralesional excisions developed local recurrences, whereas those who underwent wide resections did not. At last follow-up (mean, 91 months), available for nine patients, seven patients were alive and disease-free, one patient had died of disease, and one was alive with paravertebral metastases. Frequent histological features observed included loss of clustering of chondrocytes (nine cases), the presence of variable amounts of myxoid matrix (eight cases), peripheral hypercellularity (eight cases), tumour necrosis (six cases), and spindling of chondrocytes (four cases). Of the seven cases for which it was possible to evaluate bone permeation, six showed infiltration of bone marrow. All seven cases screened for mutations of exon 4 of IDH1 and IDH2 were found to be wild-type.

CONCLUSIONS

Histological criteria in correlation with clinical and radiological features allow the recognition of synovial chondrosarcoma. IDH1/IDH2 mutations were not present in synovial chondrosarcoma. Adequate surgical margins are important for disease control.

A Multidisciplinary Approach to Synovial Chondromatosis of the Temporomandibular Joint With Cranial Base Involvement: A Brief Review of the Literature and Case Report

Synovial chondromatosis (SC) is an infrequent, benign condition of unknown etiology affecting the synovium within articular joints. Often considered a metaplastic process, multiple cartilaginous nodules develop in the confines of the synovial membrane. In time, these cartilage nodules develop into fragments, sometimes detaching from the synovium and, thus, become loose in an adjacent synovial cavity. The temporomandibular joint (TMJ) is an unusual site of involvement, with the extracapsular compromise of the cranial base exceedingly rare. A 68-year-old woman presented with a tender mass to the left TMJ that later proved to be SC. Computed tomography illustrated a rare extension of the lesion into the middle cranial fossa. The multidisciplinary effort to remove the mass in its entirety included both oral and maxillofacial surgical and neurosurgical teams. We have reviewed the presentation, diagnosis, surgical treatment, and outcomes of the present case, with diagnostic images and photomicrographs of the lesion included. We also briefly reviewed the reported studies.