Lymphocytic panhypophysitis with clival extension and positive anti-rabphilin-3A antibodies: illustrative case.

BACKGROUND: Lymphocytic panhypophysitis (LPH) is a rare inflammatory disorder that primarily affects the pituitary gland. Extension into the cavernous sinus has been described, but clival involvement is exceedingly rare. To date, no cases of isolated clival extension have been documented. Anti-rabphilin-3A antibodies have been identified as diagnostic markers that may facilitate the diagnosis of this challenging condition.

OBSERVATIONS: An 81-year-old man presented with headache, anorexia, and fatigue. Evaluation demonstrated panhypopituitarism followed by central diabetes insipidus. MRI revealed homogeneous pituitary enlargement with isolated clival extension. Endoscopic evaluation during transsphenoidal biopsy demonstrated thickened dura mater extending from the pituitary gland to the clivus. Histopathological analysis revealed lymphoplasmacytic infiltration with a predominance of CD20-positive B cells over CD3-positive T cells and inflammatory infiltration between the clival bone trabeculae, confirming direct invasion. The serum anti-rabphilin-3A antibody test was positive. Hormone replacement therapy resulted in clinical improvement, and follow-up MRI at 3 and 6 months showed marked resolution.

LESSONS: This appears to be the first reported case of LPH with isolated clival extension. Intraoperative dural thickening and histological evidence of trabecular bone infiltration suggest a potential pathway for extrapituitary extension. Anti-rabphilin-3A antibody testing can support diagnosis, particularly in such atypical presentations. https://thejns.org/doi/10.3171/CASE25737.