Benign hand tumors Myxoma Juxta-articular myxoma Soft tissue tumors Juxta-articular myxomata are benign tumors that are mostly encountered in the vicinity of larger joints. Few cases in the hand have been reported. We present a case of a juxta-articular myxoma at the metacarpophalangeal joint of the thumb in a 40-year-old man. The preoperative diagnostic work-up included 4-dimensional magnetic resonance angiography and ultrasound. The histochemical examination of the resected tumor established the diagnosis definitively. Follow-up magnetic resonance imaging scheduled with no clinical suspicion of tumor recurrence 9 months after surgery revealed no obvious recurrence. At 14 months, the patient had full motion without pain and declined further imaging.

Introduction: In most cases the diagnostic workup of pleural mesotheliomas (MPM) starts with cytological examination of pleural effusion, but histology is needed to confirm the diagnosis. The introduction of BAP1 and MTAP immunohistochemistry have become a powerful tool to confirm the malignant nature of mesothelial proliferations also in cytological specimens. The objective of this study is to determine the concordance of BAP1, MTAP and p16 expression between cytological and histological samples of patients with MPM. Methods: Immunohistochemistry of BAP1, MTAP and p16 was performed on cytological samples and compared with the corresponding histological specimen of 25 patients with MPM. Inflammatory and stromal cells served as positive internal control for all three markers. In addition, samples of 11 patients with reactive mesothelial proliferations served as an external control group. Results: Loss of BAP1, MTAP and p16 expression was found in 68%, 72% and 92% of MPM, respectively. Loss of MTAP was associated with loss of p16 expression in all cases. Concordance of BAP1 between cytological and corresponding histological samples was 100% (kappa coefficient 1; p = 0.008). For MTAP and p16 kappa coefficient was 0.9 (p = 0.01) and 0.8 (p = 0.7788), respectively. Conclusions: Concordant BAP1, MTAP and p16 expression is found between cytological and corresponding histological samples, indicating that a reliable diagnosis of MPM can be made on cytology only. Of the three markers BAP1 and MTAP are most reliable in distinguishing malignant from reactive mesothelial proliferations