Brain Pathology Case of the Month - April 2006

Contributed by Shanop Shuangshoti 1; Sukruthai Mujananon 1; Krishnapundha Bunyaratavej 2; Mookda Chaipipat 1; Surachai Khaoroptham2
1 Department of Pathology and 2 Division of Neurosurgery, Department of Surgery
     Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Published on line in April 2006


A 4-month-old female infant presented with a growing extracranial mass at the left frontotemporal region. Covered with intact skin, the lesion measured 3.5 x 3 x 3 cm; it was well-defined, bony hard in consistency, and fixed to the underlying skull. There were no other abnormal symptoms, and routine laboratory tests were within normal limits. The mass appeared sclerotic on skull film. Computerized tomography scan of the brain (Fig. 1) showed a homogeneously enhancing expansile bone tumor. The lesion caused widening of the lower part of the left coronal suture, just above the orbital roof. The patient underwent left frontotemporal craniotomy, and the mass was found to involve the frontal and temporal bones, around the inferior limb of the coronal suture, adherent to the underlying dura. The orbital roof and apex were also affected. The lesion was totally resected. The immediate postoperative course was uneventful.

On gross inspection of the fresh specimen, the mass was hard and showed gray tan cut surfaces (Fig. 2).


Intraoperative smears and imprints disclosed bimodal population of large melanin-containing epithelial cells and smaller neuroblast-like cells (Fig. 3). The former possessed abundant pale eosinophilic cytoplasm, whereas the latter appeared as round naked nuclei with finely dispersed chromatin pattern. Thick clusters of fibrovascular tissue were also evident. An intraoperative diagnosis was rendered. Permanent sections subsequently confirmed the diagnosis by demonstrating lobules of monotonous small round cells (Fig. 4), and pigmented epithelial cells with glandular formation (Fig. 5). Mitotic figures were rarely observed, 0-1/ 10 high-power field (HPF). Immunohistochemically, the small round tumor cells expressed synaptophysin (Fig. 6), while the pigmented epithelial cells were reactive for cytokeratin (Fig. 7) and HMB-45 (Fig. 8).


International Society of Neuropathology