Ochronosis: a report of a case and a review of literature.

A patient with alkaptonuria and ochronotic pigment deposited in articular cartilage and sclerae clinically manifested a serious osteoarthritis of the peripheral and axial joints and synchondrosis, typically involved in long lasting cases of this hereditary defect of homogentisic acid oxidase. This is the first patient with this disorder reported, where a non-cemented total knee prosthesis (PCAR) was applied on both knees. This was possible due to the good quality of the bone stock, which did not seem to be impaired by ochronosis. Our patient had no cardiac symptoms or murmurs, but had a slight calcification in the annulus of aorta observed with echocardiography, a useful new method for screening this disease manifestation. A third new aspect reported is the immunopathology of the synovial tissue. Small pieces of torn-off cartilage were seen embedded in the synovial stroma. This was associated with a slight hyperplasia of the C3bi-receptor positive and proline hydroxylase positive type A and B synovial lining cells. Perivenular infiltrates contained CD2 positive T lymphocytes, mostly belonging to the CD4 subset, and some C3bi-receptor positive monocytes. Activated CD25 positive and immunoglobulin light chain positive T and B lymphocytes were absent or few. Because modern medicine has much to offer to those suffering from this ancient inborn error of metabolism in the form of new specific diagnostic methods and new surgical modes of treatment, such as endoprosthesis surgery and cardiac valve replacement, we also present a literature overview of this interesting condition.