Joint contractures, osteochondromas, and B-cell lymphoma (JCOSL) is an autosomal recessive systemic disorder characterized by the development of painless fixed contractures of the joints in early childhood. There is evidence of abnormal chondrocyte homeostasis, resulting in contractures, osteopenia, and the development of osteochondromas. Laboratory studies show abnormal levels and function of B- and T-cell subsets, and patients can develop B-cell lymphomas or malignancies. Despite the abnormalities in immunologic cells, immunodeficiency is not a feature of the disease, suggesting that it can be classified as a 'primary immune regulatory disorder' (Sharma et al., 2022). [from OMIM]

Diagnosis