Synovial Mysteries: A Histopathological Insight Into Joint Lesions

Abstract

Introduction: Synovial lesions include inflammatory, infectious, degenerative, crystal-induced, and neoplastic types. Tissue samples are obtained via blind needle or ultrasound-guided biopsy. Advances in imaging, arthroscopy, and histopathology have improved diagnosis and classification, enabling tailored treatments. We hereby evaluated the histopathological spectrum of synovial lesions through retrospective analysis of synovial biopsy samples, and to correlate the findings with clinical parameters such as age, gender, and joint involvement for improved diagnostic categorization and clinical management.

Materials and Methods: This retrospective study analyzed 100 synovial biopsies received between January 2016 and December 2020 at Vinayaka Mission Kirupananda Variyar Medical College, Salem. Clinical and radiological data were reviewed, and inclusion/exclusion criteria applied. Biopsies were fixed in 10% buffered formalin, processed, sectioned at 2 microns, and stained with Hematoxylin and Eosin; two cases were also stained with Ziehl-Neelsen for AFB. Lesions were histologically classified into inflammatory, degenerative (including crystal-induced), tumor-like lesions, and tumors.

Results: Among 90 synovial biopsy cases, inflammatory conditions were most common—non-specific synovitis (18.8%) and bursitis (16.6%)—followed by rheumatoid arthritis (11.1%), septic arthritis (5.5%), tuberculosis (2.2%), and gout (4.4%). Tumor-like lesions included ganglion cysts (26.6%) and synovial lipomatosis (3.3%), while neoplasms comprised synovial chondromatosis (4.4%) and giant cell tumors (2.2%). Loose bodies were seen in 4.4%. Females showed higher rates of non-specific synovitis, bursitis, and rheumatoid arthritis, while males had more septic arthritis, tuberculosis, gout, and synovial chondromatosis. Ganglion cysts were more common in females. Inflammatory conditions spanned a wide age range. Degenerative diseases and synovial lipomatosis affected older adults, while ganglion cysts and giant cell tumors were seen in younger individuals. The hip joint was mainly affected by chronic synovitis; the knee was commonly involved in most other conditions. Rheumatoid arthritis affected small hand joints, gout the big toe, and ganglion cysts the wrists.

Conclusion: Early detection of inflammatory conditions enables effective anti-inflammatory treatment, preventing irreversible joint damage and surgery. Accurate diagnosis of rare crystal-induced lesions avoids unnecessary treatments. Early identification of neoplastic lesions can limit surgery to simple excision. Understanding common synovial lesions and their correlation with age, gender, and site is essential for proper diagnosis.