Lacunar

Lacunar is an adjective derived from the Latin lacuna, meaning a gap, hollow, or cavity. In scientific and medical contexts, lacunar describes space-like structures or phenomena that resemble gaps, or things relating to lacunae themselves.

In anatomy and histology, lacunae are the small cavities within bone tissue that house osteocytes. The osteocytes extend through tiny channels called canaliculi, forming the lacunar-canalicular system that coordinates cellular activity and nutrient exchange within the bone matrix.

In neurology and stroke medicine, lacunar infarct or lacunar stroke denotes a small subcortical brain infarct caused by occlusion of a penetrating artery due to hypertensive small vessel disease. Common locations include the internal capsule, thalamus, putamen, and pons. Clinically, lacunar strokes often produce pure motor or sensory-motor deficits and may be associated with a favorable prognosis relative to larger territorial strokes. Management focuses on controlling vascular risk factors and implementing secondary prevention strategies.

In pathology, lacunar cells are a variant of Reed-Sternberg cells found in nodular sclerosis Hodgkin lymphoma. They have abundant pale cytoplasm and usually a lobulated or folded nucleus; the term reflects a histologic appearance that can resemble lacunae around the cells on fixation.

The term lacunar thus spans multiple disciplines, always linked to the idea of a gap or space—whether a natural cavity in tissue, a small brain infarct, or a distinctive cell type.