HELIOS-Klinikum-Berlin, Franz Volhard Clinic, Department of Radiology and Department of Pathology, Medical Faculty of the Charité, Humboldt University, Berlin, Germany. Email: kettritz{at}fvk-berlin.de
Case
A 72-year-old man was referred to the nephrology service because of myoglobinuria. The referring physicians were concerned that he might develop acute renal failure. Indeed, the myoglobin concentration in a sample of urine was 4757 µg/l, whereas his creatine kinase activity was 6287 U/l and his lactic acid dehydrogenase was 936 U/l. Anti-nuclear antibody titres were markedly elevated at a titre of 1:20 000 while anti-double-stranded DNA antibodies were not present. Serum creatinine concentration and cystatin C concentrations were not elevated and he denied having dark urine. Although the dipstick was slightly positive for blood, he had only several granular casts in his urine. A serum electrophoresis showed no monoclonal protein; however, immunofixation of serum and urine was positive for kappa light chains. The total amount excreted per 24 h was <0.5 g/day. The bone marrow showed a modest increase in plasma cells.
He reported that he was no longer able to perform the 50 pushups he had regularly managed until several weeks prior to admission. Furthermore, he now noted difficulty in climbing stairs. He also reported chronic pain in the shoulder girdle and thighs. His hand strength had also decreased. His physical examination revealed normal blood pressure and heart rate. Musculoskeletal examination showed weakness in the shoulder musculature, biceps, triceps, handgrip and quadriceps. His hands also showed nail atrophy and violaceous plaques on the dorsal aspects, as shown in Figure 1. Further questioning revealed a 4 kg weight loss. In addition, the patient had been operated upon 18 months earlier for a signet-cell gastric carcinoma. The tumour was reported to be superficial and a complete resection was possible. Lymph nodes were negative and several subsequent gastroscopies showed no sign of recurrence.
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Questions
What is your diagnosis? What additional tests might help?
Answers to the quiz on the previous page
More diagnostic tests were performed to find a rationale for his muscular pain in the shoulder girdle and his thighs. An electromyogram was consistent with myopathy. A magnetic resonance image (MRI) of his shoulder musculature is shown in Figure 2. A muscle biopsy was consistent with myositis and is depicted in Figure 3
. A dermatologist consultant agreed that the patient's violaceous rash was typical for dermatomyositis. Therapy with prednisone 50 mg/day was initiated and resulted in little improvement. We attempted to establish recurrence of his tumour. However, a repeat gastroscopy with multiple biopsies was negative and no metastases were found. Still to be tried are a course of immunoglobulins and azathioprine.
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The patient's hand findings were typical [3]. The MRI scan was striking. Dermatomyositis is an inflammatory myopathy. Important is the association between dermatomyositis and cancer. Data reported by Hill et al. [4] found that 1832% of patients with dermatomyositis have had, have, or will develop a cancer. The most likely cancers are those of the ovary, lung, pancreas, stomach, colon, rectum and non-Hodgkin lymphoma. We draw attention to the fact that multiple myeloma is a non-Hodgkin lymphoma in the broader sense and several cases of multiple myeloma with dermatomyositis have been described [5]. We could not establish the diagnosis of multiple myeloma in our patient, although the presence of kappa light chains in serum and urine is intriguing. Finally, the markedly elevated antinuclear antibody titre was a prominent feature in our patient, a finding that occasionally occurs in dermatomyositis [6]. Our patient draws attention to the fact that nephrologists must above all be good internists. You never know what might turn up next.
References