Teaching Case

A 40-year-old male presents with complaint of pain in the middle of his right calf that began after a period of toe-walking while hedge-trimming. Physical exam was notable for only localized tenderness in the area. Deep vein thrombosis was excluded twice. Rest did not alleviate his pain.

Plain radiographs of the lower extremity (tibia and fibula) demonstrate no osseous or soft tissue abnormality. Further evaluation with magnetic resonance imaging was performed. Axial STIR images demonstrate a heterogenous predominately hyperintense mass centered in the soleus. T1 weighted images of the mass demonstrate T1 heterogenous signal with areas of hyperintensity likely related to internal haemorrhage. Axial, coronal and sagittal T1 weighted images demonstrate heterogenous, predominately nodular peripheral enhancement of the mass.

Originally classified as Masson’s tumour, Intravascular Papillary Endothelial Hyperplasia (IPEH) is a reactive benign vascular proliferation that often resembles angiosarcoma. This tumour only occurs confined within the vasculature lumen and is associated with an organized thrombus [1]. This entity is estimated to represent anywhere from 2-4% of vascular tumours [2]. Primary IPEH most frequently presents in the superficial soft tissues of the head, neck or fingers. Secondary IPEH occurs as a reactive outgrowth from a previous vascular lesion.

In contrast to the primary type, secondary IPEH tends to be larger and arises in deep soft tissue locations [1]. In a study of 91 cases of IPEH, the tumour had a predilection for females, with a median age of presentation of 31 years old. The most common presenting sign of IPEH is oedema of the overriding skin, often with blue or red discoloration. Pain accompanies this pathology in roughly one-third of cases [3].

Despite the fact this pathology is relatively common in the general population, IPEH is rarely imaged [2]. On ultrasonography, the lesion appears hypoechoic with mixed or peripheral associated vascularization. The lesion appears as a small, spherical mass on MRI. On T2-weighted images, IPEH exhibits hyperintensity peripherally with discrete foci of low to intermediate intensity. Peripheral enhancement reflects vascular proliferation along the lesion’s borders, while the unpredictable pattern of the thrombus organization and vascular proliferation within the vessel accounts for the variability of the central signal [1]. Though T1-weighted imaging may vary, IPEH typically demonstrates hypointense or heterogeneous signal, possibly due to haemorrhage contained within the lesion [1,2].

Once correctly identified as IPEH, the prognosis is excellent. When necessary, simple excision of the mass generally proves curative. In the rare cases in which the lesion is refractory, one should highly suspect another underlying vascular pathology. Such cases are predicated upon treating the underlying pathology [4]. Secondary IPEH tends to recur at greater indices relative to the primary form [3].

Written informed patient consent for publication has been obtained.