Intramuscular cavernous haemangioma of the temporal muscle presenting with bone erosion and atypical radiological features

Background Intramuscular cavernous haemangiomas are rare benign vascular tumours, particularly when arising in the temporalis muscle or infratemporal fossa. Radiological diagnosis is challenging because imaging features often overlap with those of other benign soft-tissue lesions, and bone involvement is considered unusual. To our knowledge, bone erosion associated with temporalis intramuscular cavernous haemangioma has been rarely described in the literature. Case presentation : We report the case of a 37-year-old woman with a slowly progressive left temporo-infratemporal mass evolving over 12 years and repeatedly diagnosed as a lipoma. Cross-sectional imaging revealed a deeply located, highly vascularised intramuscular lesion with atypical radiological features, notably erosion of the adjacent temporal bone and the greater wing of the sphenoid. Magnetic resonance imaging demonstrated a heterogeneous mass, hypointense on T1-weighted sequences and markedly hyperintense on T2-weighted sequences, with intense heterogeneous enhancement following gadolinium administration. Because of the apparent aggressive imaging behaviour, malignant or invasive lipomatous tumours were initially suspected. Surgical management consisted of maximal safe excision via an infratemporal approach, leaving a small deep residual component due to excessive vascularity. Histopathological examination confirmed a cavernous intramuscular haemangioma. Post-operative follow-up MRI demonstrated a small, stable residual lesion without progression. Conclusion This case emphasises the importance of radiological evaluation in intramuscular haemangiomas occurring at rare locations. Although cavernous haemangiomas are classically non-invasive, associated bone erosion may occur and represent a diagnostic pitfall, potentially mimicking aggressive neoplastic processes. Awareness of this atypical imaging presentation can help avoid misdiagnosis and guide appropriate surgical management.