DIAGNOSIS Capillary hemangioma
The majority of capillary hemangiomas arise in the skin, scalp, or oral mucosa and typically appear within a few months of birth (9). In these areas, such lesions have been reported to occur in 1.1 to 2.6% of full-term neonates, with an estimated frequency of 10 to 12% within the first year of life. They typically demonstrate rapid growing up to 6 to 8 months, followed by a plateau phase between 8 and 12 months. Occasionally, these lesions are completely regressed in 5 years (5). The natural history of capillary hemangiomas occurring outside the central nervous system has been well characterized by proliferative and involutional phases (4). Only 14 microscopically proven cases have been reported in the literature. Capillary hemangiomas are believed pathologically to be hamartomatous proliferations of vascular endothelial cells. Histologically, a capillary hemangioma is composed of capillary-size vessels lined by a single layer of benign endothelial cells (10). Blood vessels vary widely in size from small lumina lined with plump endothelial cells to dilated vessels lined with flattened endothelium (1). GFAP immunostaining showed no glial tissue present within the lesions (2). Microscopically, capillary hemangiomas in the central nervous system must be distinguished from highly vascular neoplasm, which include hemangioendotheliomas, hemangiopericytomas, and hemangioblastomas (7). In this case, histological examination failed to show large vacuolated stromal cells characteristic of capillary hemangioblastomas, primitive vascular differentiation characteristic of hemangioendotheliomas and storiform architecture in hemangiopericytomas. Tumors occurring in the infundibular recess or pituitary stalk include pituitary adenomas, germ cell tumors, pituicytomas, and granular cell tumors. Pituicytomas are noninfiltrative sellar or parasellar tumors arising from the neurohypophysis. Pituicytoma is derived from pituicyte, which is a specific glial cell that accounts for the majority of nucleated cells in the neurohypophysis. Pituicytes have been identified as GFAP positive, spindle, or stellate cells (8). Granular cell tumors are composed of densely packed polygonal cells with eosinophilic, granular, diastase-resistant cytoplasm and perivascular lymphocytic aggregates are a common feature (3). These tumors typically express S100 protein and CD68 (KP-1) (6). Only thin-walled capillaries were demonstrated in this case that was negative for S100 protein, CD68 (KP-1) and GFAP. In summary, we have reported on a capillary hemangioma in the infundibular recess and pituitary stalk. Capillary hemangiomas should be included as a rare differential diagnosis in patients with well-enhanced homogeneous lesions in the infundibular recess and pituitary stalk.
Contributed by Yun-Ho Lee, Young Seok Park, Dong-Seok Kim, Yong-Gou Park and Kyu-Won Shim