Pituicytoma is a rare low-grade (WHO grade I) sellar region
glioma. Among sellar
tumors, pituitary adenomas, mainly
prolactinomas, may show
amyloid deposits.
Gelsolin is a ubiquitous
calcium-dependent
protein that regulates actin filament dynamics. Two known gene point mutations result in
gelsolin amyloid deposition, a characteristic feature of a rare type of
familial amyloid polyneuropathy (FAP), the Finnish-type FAP, or hereditary
gelsolin amyloidosis (HGA). HGA is an autosomal-dominant systemic
amyloidosis, characterized by slowly progressive neurological deterioration with corneal lattice dystrophy,
cranial neuropathy, and
cutis laxa. A unique case of pituicytoma with marked
gelsolin amyloid deposition in a 67-year-old Chinese woman is described. MRI revealed a 2.6-cm well-circumscribed, uniformly contrast-enhancing solid sellar mass with suprasellar extension. Histologically, the lesion was characterized by solid sheets and fascicles of spindle cells with slightly fibrillary cytoplasm and oval nuclei with pinpoint nucleoli. Surrounding brain parenchyma showed marked reactive piloid
gliosis. Remarkably, conspicuous
amyloid deposits were identified as pink homogeneous spherules on light microscopy that showed apple-green birefringence on
Congo red with polarization. Mass spectrometric-based proteomic analysis identified the
amyloid as
gelsolin type. Immunohistochemically, diffuse reactivity to
S100 protein and TTF1, focal reactivity for GFAP, and no reactivity to EMA,
synaptophysin, and
chromogranin were observed. HGA-related mutations were not identified in the
tumor. No recurrence was noted 14 months after surgery. To the knowledge of the authors,
amyloid deposition in pituicytoma or
tumor-associated
gelsolin amyloidosis has not been previously described. This novel finding expands the spectrum of sellar
tumors that may be associated with
amyloid deposition.