Soft‐tissue angioleiomyoma of the hand as a rare differential diagnosis of haemophilic pseudotumour

The benign vascular tumours known as angioleiomyomas, which originate from smooth muscle cells of arterial or venous walls are rare, particularly in the region of the hand. Frequently, the diagnosis is only made after surgical extirpation and histological assessment. The occurrence of an angioleiomyoma in a haemophiliac has not yet been reported, to our knowledge. A 62‐year‐old patient with a haemophilia B complained of increasing pain in the vicinity of the soft tissue covering the carpo‐metacarpophalangeal joint of his left palm. In the T1‐weighted magnetic resonance images a hypointense well‐demarcated mass was found, showing a homogenous enhancement after intravenous application of contrast medium. T2‐weighted images showed a hyperintense signal. Based on clinical and radiographic findings, the tumour was initially thought to be a haemophilic pseudotumour arising from a prior local haematoma. Intraoperatively, the mass was found to be solid, and histological assessment diagnosed an angioleiomyoma, without signs of malignant transformation. Descriptions of the clinical symptoms of angioleiomyoma in an extremity vary considerably in the literature. Alhough rare, the vascular leiomyoma should therefore be contemplated in the differential diagnosis in patients with a solid nodular lesion of unclear aetiology in arms or legs. Especially in a haemophiliac patient, the growth can easily be mistaken for a pseudotumour because of its clinical and radiological similarities.