[Diagnostic difficulties in ochronosis alcaptonurica].
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Alkaptonuria, a rare autosomal-recessive disorder caused by mutations in the HGD gene and a deficiency of homogentisate 1,2-dioxygenase, is characterized by accumulation of homogentisic acid (HGA), ochronosis, and destruction of connective tissue resulting in joint disease. Certain medications have been reported to cause cutaneous hyperpigmentation resembling that of alkaptonuria. We present 5 such cases. Eighty-eight patients with a possible diagnosis of alkaptonuria were examined at the National Institutes of Health Clinical Center between June 2000 and March 2004. The diagnosis of alkaptonuria was confirmed or ruled out by measurement of HGA in the urine. Five patients with findings consistent with ochronosis, including pigmentary changes of the ear and mild degenerative disease of the spine and large joints, were diagnosed clinically as having alkaptonuria, but the diagnosis was withdrawn based on normal urine HGA levels. All 5 patients were women who had taken minocycline for dermatologic or rheumatologic disorders for extended periods. Minocycline-induced hyperpigmentation should be considered in the differential diagnosis of ochronosis. This could be of increased significance now that minocycline and other tetracyclines have been proposed as therapeutic options for rheumatoid arthritis, bringing a new population of patients with ochronosis and arthritis to medical attention with the potential, but incorrect, diagnosis of alkaptonuria.
Ochronotic spondyloarthropathy is a rare metabolic disease with the musculoskeletal manifestations of alkaptonuria. Ochronotic arthropathy patients may have spinal abnormalities similar to ankylosing spondylitis (AS). The proof of sacroiliac involvement or bamboo spine appearance is not sufficient either for diagnosis of ankylosing spondilitis or exclusion of ochronosis. In this report, the case of a 54-year-old woman having ochronosis, with clinically more recognizable axial arthropathy resembling AS, is presented, and the history, clinical presentation, diagnostic techniques, and distinctive diagnosis are reviewed.
Alcaptonuria is a hereditary disease, also known as black hip, where there is an accumulation of homogentisic acid pigmentation in joint cartilages. We describe a 74-year-old woman who showed acute destruction of her left hip joint. She received a total hip arthroplasty on her right side in July 2000, and was diagnosed with ochronosis. Her postoperative follow-up was at our institutions outpatient department. She first complained of increasing groin pain in July 2005, after which she had a left total hip arthroplasty in October 2005. Histopathologically, samples from this patient showed "fragmentation and cleft formation" in the cartilage of the femoral head. In addition, the samples revealed a remarkable degradation of proteoglycan, which is the secondary most abundant constituent of extra cellular matrix. These findings suggested that "cleft formation", where cracks develop toward the center, caused an acute destructive arthropathy with morphological fragility suggestive of ochronosis.
We investigated skeletal involvement in five male and two female patients with ochronosis, aged 26-82 years. The main parameters of mineral metabolism, together with biochemical markers of bone resorption (urinary N-telopeptides of type I collagen) and formation (serum bone isoenzyme of alkaline phosphatase and serum osteocalcin) were evaluated. In the same subjects lumbar spine and femoral bone mineral density (BMD) were also measured by dual energy X-ray absorptiometry. All patients but the younger 26-year-old patient had lower than normal bone mass at femoral neck and total hip, showing marked osteopenia in three cases and osteoporosis in the remaining three cases. However, at lumbar spine BMD measurement provided spuriously overestimated results, because of intervertebral disc calcification and osteophyte formation. As far as biochemical markers of bone turnover are concerned, the most relevant finding was the increased N-telopeptides of type I collagen urinary excretion. Our results suggest that ochronosis may be associated with increased bone resorption rate leading to an accelerated bone loss. A role of the homogentisic acid polymer deposit in bone matrix and cells, possibly with osteocyte damage and interference in collagen metabolism, might be hypothesized.
AIM: To study the spine alterations in alcaptonuria with traditional radiology and magnetic resonance (MR), comparing the results of the two techniques. PATIENTS AND METHODS: Five patients (4 males, 1 female, mean age 51 years) underwent the examinations. For the study with X-rays we performed anteroposterior and lateral scan and the images have been studied making reference to a radiographic score; it examines the alterations of the joint space and the presence of calcifications. MR scan, oriented in the three spatial planes, were performed using spin echo T1-weighted and spin echo T2-weighted sequences. RESULTS: Both MR and X-rays pointed out, in the cases with known diagnosis, the typical alterations of the ochronosis: narrowing of the articular spaces, even osseous ankylosis, calcifications of the discs, osteophytosis, multiple disc protrusions and reactive sclerosis of the articular surfaces, evident above all to dorso-lumbar tract; nevertheless MR has been more accurate than X-rays for individualizing the lesions and recognizing alterations, such as the thickness of the anterior longitudinal ligament. In the case of new diagnosis, the MR is fundamental to recognize typical signs of the ochronotic arthropathy not well detected by X-rays. CONCLUSIONS: Imaging techniques, first of all the MR, are essential in the differential diagnosis of ochronosis vertebral lesions with other articular diseases.
Radiologic examination of an Egyptian mummy showed characteristic radiologic changes seen in ochronosis. Desiring to confirm the diagnosis of ochronosis, punch biopsy samples of ochronotic mummy bone were removed for biochemical analysis. An organic solvent extraction procedure was developed to selectively isolate mummy ochronotic pigment, and spectroscopic methods were used to characterize the pigment as a homogentisic-acid--derived polymer.
Ochronosis is the dark pigmentation of connective tissues in patients with alkaptonuria. The latter is an autosomal recessive deficit of phenylalanine and tyrosine metabolism with various clinical manifestations. We report on a 63-year-old man with familial ochronosis, who presented with a terminal degenerative right hip joint; his older brother had already been successfully treated at our department by total hip replacement. The postoperative course was uneventful and satisfactory for both.
Alkaptonuria is a human hereditary metabolic disease characterized by a very high urinary excretion of homogentisic acid, an intermediary product in the metabolism of tyrosine, in association with ochronosis and arthritis. This disease is due to a deficiency in the enzyme homogentisic acid oxidase and is inherited as an autosomal recessive condition. We have found a new recessive mutation (aku) in the mouse that is homologous to human alkaptonuria, during a mutagenesis program with ethylnitrosourea. Affected mice show high levels of urinary homogentisic acid without signs of ochronosis or arthritis. This mutation has been mapped to Chr 16 close to the D16Mit4 locus, in a region of synteny with human 3q.
Alkaptonuria is a rare disorder of metabolism characterized by deficiency of homogentisic acid oxidase. This leads to the characteristic features like darkening of urine, ochronosis and arthropathy. Darkening of urine is one of the first symptoms noticed by the parents of the child suffering from this disorder. Ochronosis is seen in various organs like eyes, skin, tendons and joints. A case of 10 year old boy is reported who was brought to this clinic with the presenting complaint of bluish discoloration of sclerae. This discoloration led to eliciting positive history of dark urine off and on. Further investigations confirmed alkaptonuria.
In alkaptonuric ochronosis, the absence of homogentisic acid oxidase results in the accumulation of homogentisic acid in the body. Associated renal failure is rare and usually occurs in the later stages of the disease. We report a 19-yr-old girl who presented initially with severe renal failure, without family or past history of illness. There was no significant proteinuria or hematuria. No clinical evidence of pigmentation such as skin and subcutaneous cartilages was noted. However, pigment deposits were identified in the renal biopsy specimens obtained within a week after admission and another after a month. Two months later the peritoneal dialysis fluid and skin progressively darkened, suggesting ochronosis. This was confirmed by the detection of homogentisic acid in the serum and urine. The patient expired in renal failure. Renal biopsy tissues showed diffuse chronic tubulo-interstitial disease characterized by widespread tubular atrophy, interstitial fibrosis, and a moderate degree of inflammation. Many tubular cells contained brown, coarsely granular ochronotic pigment (OP) and a few pigment casts were in the lumina. Similar deposits were also in the interstitium and within histiocytes. Ultrastructural studies of the glomeruli revealed small sparse OP deposits in the visceral and parietal epithelial cells, mesangial cells, and rare extracellular and basement membrane deposits. The tubulointerstitial changes were varied: atrophy and dilatation of tubules, varying degrees of lysosomal OP and degeneration of tubular cells, casts containing OP with crystalline material, histiocytes distended with OP, and free interstitial pigment deposition.(ABSTRACT TRUNCATED AT 250 WORDS)