Erythema nodosum associated with myelodysplastic syndrome: a case report.

When presenting, the haemoglobin level was 8.1 g/dl, reticulocytes 0.4%, white blood cell count 17.6 × 10 cells/l with 4% blast cells, 2% myelocytes, 77% polymorphonuclear leukocytes, 5% band cells, 6% monocytes and 7% lymphocytes. The platelet count was 30 × 10/l. Further laboratory tests revealed a lactate dehydrogenase (LDH) level of 251 U/l (normal < 250 U/l), a serum ferritin level of 4720 mg/l (normal 15–160 mg/l) and a C-reactive protein (CRP) level of 13 mg/dl (< 0.5 mg/dl). No other reason for the erythema nodosum was found. Rheumatoid factor and anti-neutrophil cytoplasmic antibodies (ANCA) were not detectable; complement factors C3 and C4 were normal. The anti-streptolysine level was 26 IU/ml (normal < 360 IU/ml); the Mantoux tuberculin skin test, Lyme serology, Mycoplasma pneumoniae, Chlamydia pneumoniae and trachomatis serology were negative. Chest X-ray and chest computed tomography (CT) scan revealed no sign of pneumonia or sarcoidosis. Colonoscopy demonstrated bland diverticulosis, but no signs of inflammation. The histological examination of mucosa biopsies displayed no inflammatory bowel disease. The bacteriological stool examination was inconspicuous. No malignancy was found in the chest CT scan, the colonoscopy and the abdominal sonography. The lenalidomide therapy was terminated about 4 years before the onset of the erythema nodosum, making a causal link unlikely. The bone marrow biopsy from January 2010, which was taken after the onset of the erythema nodosum, showed no disease progression in comparison to the bone marrow biopsy from September 2009. The International Prognostic Scoring System (IPSS) indicated an intermediate risk II. After immunosuppressive treatment with prednisone 40 mg daily, the skin lesions and the ankle pain as well as the laboratory inflammatory signs improved within days. The total white blood cell count dropped to a normal value of 9.2 × 10 cells/l with 2% blast cells, 1% myelocytes, 70% polymorphonuclear leucocytes, 3% band cells, 5% monocytes and 15% lymphocytes.