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Year : 2006  |  Volume : 16  |  Issue : 4  |  Page : 573-576
Pictorial essay: Alkaptonuria

Radiodiagnosis IGMC and Mayo Hospital NAGPUR Consultant Radiologist, Amarjyoti x-ray and Sonography clinic, Wardha road, Dhantoli Nagpur-12, India

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Date of Submission03-May-2004
Date of Acceptance20-Oct-2006

Keywords: Alkaptonuria

How to cite this article:
Phatak S V, Kolwadkar P K, Hemnani T J, Phatak M S, Hemnani J T. Pictorial essay: Alkaptonuria. Indian J Radiol Imaging 2006;16:573-6

How to cite this URL:
Phatak S V, Kolwadkar P K, Hemnani T J, Phatak M S, Hemnani J T. Pictorial essay: Alkaptonuria. Indian J Radiol Imaging [serial online] 2006 [cited 2021 Jan 22];16:573-6. Available from:

   Introduction Top

Alkaptonuria is a metabolic disorder of tyrosine and phenylalanine metabolism in which there is an absence of enzyme homogentisic acid oxidase, the enzyme deficiency results in an excessive accumulation of homogentisic acid in urine, which causes urine to turn black on standing. The melanin like oxidized polymer of homogentisic acid binds to cartilage and other tissues leading to blue green discoloration known as ochronosis [1] A few case have been discovered in childhood because of brownish or black discoloration of diapers. The condition is usually asymptomatic until middle age when the patient becomes poorly nourished and appears chronically ill. The skin becomes mottled yellowish or brownish colour, particularly over head, neck and torso and to a lesser degree over the arms and legs. The ear lobe appears nodular and rigid and becomes a discolored grayish blue colour. The nose also acquire blueish tint due to deposit of homogentesic acid and sclerae likewise assume blue or purplish appearance with triangular brownish patches. Clubbing of fingers occurs and there is discoloration of hands, axillae and genital region because of accumulation of pigment. [2]

Discussion: -Alkaptonuria is a rare autosomal recessive metabolic disease. Since 1958 when the first case was described approximately 600 cases have been reported. [3] Its incidence is 1:250000 to 1:100000 persons [4] In Alkaptonuria Homogentesic acid is converted into benzoquinone acetic acid and polymerized. Ochronosis is the result of binding and chemical reaction of benzoquinone and its polymers with connective tissue [5] Typical sites of Ochronotic pigment deposition are the eyes, skin, skeletal cartilage and virtually all collagen rich organs [1] Other systems that may be involved include the auditory, genitourinary, cardiovascular and respiratory tracts. [6],[7],[8]. Cardiac involvement occurs due to deposition of polymerized homogentesic acid in aortic, mitral and pulmonic valve. It usually leads to rigidity and calcification. [9] Chronic progressive joint destruction is associated with pigmentation of connective tissue. Pigmented cartilage is brittle and frequently develops fissures with cellular proliferation, leading to degenerative arthropathy. Pigment may be deposited in tendon attachments as well as in the involved joints. [1] There are no roentgen changes early in the disease. In the second and third decade the most distinctive finding is the laminated calcification of multiple intervertebral discs. [Figure - 2],[Figure - 7] Commonly all the interspaces are affected and dramatically emphasized by the osteoporosis in the adjoining vertebrae. Universal calcified discs and osteoporosis in young individual are pathognomonic of Ochronosis [10]. The radiographic picture in the spine in Ochronosis is characteristic. Pigment is deposited in annular fibrosis and nucleus pulposus of multiple intervertebral disc spaces causing calcification and ossification in thoracolumbar region. [1] Various causes of intervertebral disc calcification include ochronosis, CPPD crystal deposition disease, Acromegaly, Haemochromatosis, Hyperparathyroidism, Poliomyelitis, Amyloidosis and spinal fusion [11] This is frequently associated with vacuum phenomenon and subchondral sclerosis. [1] [Figure - 8] Vacuum phenomenon is a radiological appearance-involving spine in which linear or circular radiolucent collection appears within intervertebral discs. Vacuum phenomenon is a reliable indicator of disc degeneration and is very rare in presence of discal infection or tumor. It is seen in various diseases including intervertebral osteochondrosis, intraspinal disc herniation, spondylosis deformans, Schmorls nodes, Osteoarthritis, and Ischemic necrosis. [12] The disc spaces are very narrow. Spur formation is not particularly prominent. The sacroiliac joints are usually spared. Calcification, subchondral bone destruction and fusion of symphysis pubis may be seen. Involvement of enthesis (Bone tendon interface) may be seen with periostitis in the regions of trochanters, calcaneus and pelvis. Marked destructive changes are frequent in the knees, shoulders and hips but rare in more peripheral joints .The arthropathy is usually associated with rapid joint destruction. Osteophytes and subchondral cysts are rarely as large as those seen with osteoarthritis. Intraarticular calcium pyrophosphate crystals may be seen in close relation to the pigment deposition in large joints. [1] Degenerative changes occur in shoulder joint. Since osteoarthritis is rare in shoulder it suggests ochronosis in young patients. Cartilage destruction produces joint space narrowing, secondary eburnation and spur formation at glenoid. Hypertrophic changes occur at humeral head, which may be flattened. Small calcifications occur in periarticular soft tissue .The small joints of extremities usually show only periarticular swelling without significant narrowing of joint space. In older patients massive lipping and ankylosis of spine results in severe dorsal kyphosis with a decrease in lumbar lordosis. [10]

   References Top

1.Murray K Dalinka, Antonio J.Reginato, David A Golden Calcium Deposition diseases Seminars in Roentgenology, Vol XVII, No.1 (January) 1982:42-44  Back to cited text no. 1    
2.Bernard S.Epstein Ochronosis In The spine, A radiological text and atlas third edition Lea and Febiger 1969:304-5  Back to cited text no. 2    
3.La Du BN. Alcaptonuria. In: Scriver CR, Beaudet AL, Sly WS, Valle D, Eds. The Metabolic Basis of Inherited Disease. 6th Ed. New York, NY: McGraw-Hill Book Co; 1989:775-790.  Back to cited text no. 3    
4.Albers SE, Brozena SJ, Glass LF, Fenske NA. Alkaptonuria and ochronosis: case report and review. J Am Acad Dermatol. 1992; 27:609-614. Medline   Back to cited text no. 4    
5.Zannoni VG, Lomtevas N, Goldfinger S. Oxidation of homogentisic acid to ochronotic pigment connective tissue. Biochim Biophys Acta. 1969; 177:94-105. Medline  Back to cited text no. 5    
6.O'Brien WM, La Du BN, Bunim JJ. Biochemical, pathologic and clinical aspects of alcaptonuria, ochronosis and ochronotic arthropathy: review of world literature (1584-1962). Am J Med. 1963; 34:813-838.   Back to cited text no. 6    
7.Venkataseshan VS, Chandra B, Graziano V, et al. Alkaptonuria and renal failure: a case report and review of the literature. Pathology. 1992; 5:464-471.   Back to cited text no. 7    
8.Gaines JJ, Pai GM. Cardiovascular ochronosis. Arch Pathol Lab Med. 1987; 111:991-994. Medline  Back to cited text no. 8    
9.Kenny D, PtacinMJ, Bamrah VS, Almagro U Cardiovascular ochronosis: a case report and review of medical literature Cardiology1990; 77(6): 477-83  Back to cited text no. 9    
10.Jack Edeiken, Philip J Hodes OchronosisIn Roentgen diagnosis of dieeases of bone second edition, Asian edition Williams and Wilkins Company Baltimore 1973:785-6  Back to cited text no. 10    
11.WeinbergerA, MyersAR :Intervertebral disc calcification in adults a review Semin arthritis Rheum 1975; 18:69-75  Back to cited text no. 11    
12.Vacuum phenomenon: The encyclopedia of medical imaging Vol III: 1  Back to cited text no. 12    

Correspondence Address:
S V Phatak
Radiodiagnosis IGMC and Mayo Hospital Nagpur Consultant Radiologist, Amarjyoti x-ray and Sonography clinic, Wardha road, Dhantoli Nagpur- 12
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0971-3026.32272

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  [Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8]


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