A Rare Case of Sarcoidosis With Aggressive Bony Lesion in the Frontal Bone.

Sarcoidosis is a multisystem granulomatous disorder that can rarely involve bone, particularly the skull, where lesions may closely resemble malignant or infectious processes. We report a 60-year-old man with established multisystem sarcoidosis who presented with acute left-sided headache, diplopia, and periorbital pain. Neuroimaging demonstrated a poorly defined left frontal bone lesion with homogeneous post-contrast enhancement. Laboratory evaluation revealed elevated angiotensin-converting enzyme levels, and a supraclavicular lymph-node biopsy confirmed non-caseating granulomas. As systemic sarcoidosis had already been histologically established and the radiologic features were characteristic, direct biopsy of the cranial lesion was deferred. The patient was treated with oral corticosteroids, resulting in rapid improvement in pain and cranial-nerve function. This case highlights the importance of recognising cranial osseous sarcoidosis as a potential mimic of malignancy to avoid unnecessary invasive procedures and emphasises the value of timely corticosteroid therapy and coordinated multidisciplinary management.