Indian Journal of Medical Sciences Medknow Publications on behalf of Indian Journal of Medical Sciences Trust ISSN: 0019-5359 EISSN: 1998-3654 Vol. 59, Num. 5, 2005, pp. 211-213

Indian Journal of Medical Sciences, Vol. 59, No. 5, May, 2005, pp. 211-213

Letter To Editor

Cutaneous markers in Ochronosis

Isaac Jebaraj, Rao A

Departments of Orthopaedics, Christian Medical College, Vellore, Tamilnadu - 632 004

Correspondence Address: Departments of Orthopaedics, Christian Medical College, Vellore, Tamilnadu - 632 004, ijebaraj@hotmail.com

Code Number: ms05031

Sir,

A 40-year-old woman presented with low backache of five-year duration with pain in the knee, shoulder and ankle joints on both sides. On examination she was found to have thickened ear lobule with restricted mobility of pinna [Figure - 1]. There was black pigmentation in the palmar aspect of the right index finger [Figure - 2]. She also had hyperpigmented plaques with adherent scales in the left palm which was most obvious in the little finger [Figure - 3]. Plain radiograph of the lumbar spine showed intervertebral disc calcification [Figure - 4]. Her urine sample collected in the outpatient turned black on standing for about 12 h. She was diagnosed to have ochronosis and was positive for urine HPLC (high profile liquid chromatography) test for homogentisic acid (HGC).

Alkaptonuria is a rare hereditary metabolic disorder, clinically manifested by spondyloarthropathy and soft tissue ochronosis. The biochemical defect is the absence of enzyme homogentisic acid oxidase which leads to accumulation of HGC in skin and the various connective tissues of the body. Our case report highlights unusual cutaneous signs of ochronosis. Ochronotic pigmentation is observed in the third and fourth decade in the skin, sclera, and ears. The chemical characteristics of this pigment resemble melanin and it is presumed to be a polymer derived from HGC. When the urine of affected persons is allowed to stand, the HGC is oxidized to a melanin-like product, which causes the urine to gradually turn black.[1] This pigment has an affinity to cartilage and connective tissues which in turn destroys the auricular cartilage and produces degeneration of the tendons. Although the patients are asymptomatic, they develop signs of arthritis and tendon rupture in middle age. There are three stages in the pathogenesis of ochronosis.[1] Stage 1 is mainly alkaptonuria presenting as increased excretion of HGC in urine. Stage 2 is ochronosis characterized by deposition of HGC in connective tissue and cartilage. Stage 3 is spondyloarthropathy involving the axial and appendicular skeleton. In our experience the commonest joint to be involved is the knee joint, next only to the spine. Occasionally, the shoulder and hip may also develop secondary osteoarthritis. The tendoachilles undergoes degenerative rupture which may be the only presenting symptom.

In the ear the cartilage appears thickened with slate blue or grey discoloration leading to restricted mobility of the pinna. Occasionally, these patients will show pigmentation on the palmar and plantar surfaces which appear as a coal black-like "tattoo" mark, coined as palmoplantar pigmentation.[2],[3] These may be associated pitting and hyperpigmented plaques with adherent scales. More commonly patients also show subcutaneous nodules in the region of the popliteal fossa or achilles tendon. History of drug ingestion is mandatory in patients with palmoplantar pigmentation since minocycline-induced pigmentation is a well known entity masquerading as alkaptonuria.[4] Rarely, an intramuscular injection of quinine can lead to bluish black pigmentation in the buttocks resulting in exogenous ochronosis.[5] In conclusion one should keep in mind the possibility of ochronosis when a patient presents with low backache, joint pains (spondyloarthropathy) and cutaneous signs as described above.

REFERENCES

Copyright 2005 - Indian Journal of Medical Sciences

The following images related to this document are available:

Photo images