Background: Plasma cell granuloma, one of the subtypes of inflammatory pseudotumor, is non-neoplastic proliferation of plasma cells and occurs extremely rarely in the intracranial space. We encountered a case of plasma cell granuloma in the pituitary gland, which initially presented with left oculomotor palsy.
Case description: A 34-year-old female presented with left ptosis. Magnetic resonance image (MRI) demonstrated an intrasellar mass extending to the pituitary stalk with dural enhancement. The lesion was subtotally resected by a transsphenoidal approach. Histopathological findings showed that the resected mass consisted of mature plasma cells, and some cells had infiltrated the surrounding normal pituitary tissue. Immunohistochemical study demonstrated that these cells were positive for leukocyte common antigen, kappa and lambda light chains of IgG, indicating polyclonality of these plasma cells.
Conclusions: We propose that, in the case of an intrasellar mass with unusual neurological symptoms including oculomotor palsy, inflammatory disease of the pituitary gland such as plasma cell granuloma should be included in the differential diagnosis.