Microvascular Occlusive Lesions in Primary Thrombocythaemia

Summary. Although haemorrhagic manifestations are common in primary thrombocythaemia, microvascular occlusive lesions often leading to peripheral gangrene are frequent and can be the sole clinical manifestation of the disease. Twenty‐seven patients were followed for periods of 6 months to 14 years. The microvascular occlusive group of nine patients presented with distal gangrene of toes, a purple mottled appearance of the skin resembling lesions of livedo reticularis pain aggravated by warmth and erythromelalgia. These ischaemic lesions appearing without demonstrable arterial disease indicate a primary role of the platelets in the occlusive process. None of these patients presented with haemorrhagic symptoms but many later showed abnormal post‐traumatic bleeding. The ischaemic lesions including the gangrenous toes were completely reversed by treatment and did not recur. Ten patients presented with characteristic features of primary haemorrhagic thrombocythaemia. The haemorrhagic manifestations ranged from small, recurrent and multiple ecchymoses to recurring gastro‐intestinal blood loss, massive spontaneous haematoma and excessive post‐operative bleeding. An asymptomatic group of six patients were diagnosed during routine investigation of other disorders. In none of them did a causal relationship seem possible. The miscellaneous group consisted of two patients with the characteristic clinical and haematological features of primary thrombocythaemia who when successfully treated, developed polycythaemia. Busulphan was shown to be effective in controlling the proliferative process in all groups.