[The radiographic report of soft tissue tumor on the legs in a case of cutaneous polyarteritis nodosa].
A 55-year-old male was admitted to our hospital because of arthralgia, rash, and painful tumor in the legs. On admission, skin lesions involving dark erythematous macules and a tender mass of 3 by 5 cm were present. Laboratory findings included hemoglobin of 11.2 g/dl, white blood cell count of 6200/microliter, erythrocyte sedimentation rate (ESR) of 88 mm/hour, and normal results of renal function tests. Hepatitis B surface antigen, anti-nuclear antibody (ANA), and perinuclear pattern antineutrophil cytoplasmic autoantibody (ANCA) were negative. A T 1-weighted magnetic resonance image (MRI) showed iso-intensity areas that increased in intensity on T 2-weighted images of the M. gastrocnemius. The angiographic appearance of tumor staining with some degree of luminal irregularity in the posterior tibial artery suggested a diagnosis of soft tissue neoplasm. Biopsy specimens of the right leg lesion were consistent with necrotizing arteritis of both small and medium-sized vessels. Treatment with prednisolone and cyclophosphamide resulted in the disappearance of the skin lesions and the improvement of laboratory data. At first, classical polyarteritis nodosa was considered histologically. However, lesions were limited to skin, muscles, and joints, and there has been no evidence of systemic disease for 1.5 years; consequently, cutaneous form of polyarteritis nodosa was diagnosed. Reports of soft tissue tumors on the legs of patients with polyarteritis nodosa are quite rare. The interesting radiographic findings of cutaneous polyarteritis nodosa were reported.