Brain Pathology Case of the Month - July 2011

Contributed by Carlos H. Carvalho, MD1, Leonardo M Batista, MD, DDS1, Antje Bornemann, MD, PhD2, Marcus André Acioly, MD1, Marcos Tatagiba, MD, PhD1
1 Department of Neurosurgery, 2 Institut of Brain Research, Eberhard Karls University Hospital, University of Tübingen, Tübingen, Germany


A 58- year-old man with clinical diagnosis of phacomatosis pigmentovascularis (PPV) was admitted to our neurosurgical department with a 5-year history of tinnitus, progressive hearing loss on the right and headaches. On physical examination, multiple melanocytic and vascular nevi (more than150) together with 20 atypical nevi, extensive port-wine stains on the first and third divisions of the trigeminal nerve, and blue spots over his right shoulder, neck, head, ear and face were identified (Figure 1). No ocular pigmentation, increased ocular pressure or seizures were observed. On neurological evaluation, only hearing loss was found.


Brain MRI revealed a dumbbell-shaped tumor located into the right jugular foramen extending towards the cerebellopontine angle (CPA) and extracranially. The lesion demonstrated a heterogeneous signal on T1 (Figure 2) and isointensity with the grey matter on T2-weighted MR images (Figure 3) leading to erosion and expansion of the jugular foramen. After contrast administration, homogeneous enhancement of the mass was observed (Figures 4 and 5).


A standard right retrosigmoid approach was performed while in the semi-sitting position. After dural opening and arachnoid dissection, several pigmented spots were observed over the tumor capsule (Figure 6). The tumor was completely removed with anatomical preservation of the lower cranial nerves by using intraoperative neuromonitoring. The patient was affected by dysphonia and swallowing dysfunction due to a permanent vagus nerve neuropathy that lasted for 13 months after the surgery. There were no signs of tumor recurrence in an MRI performed 8 months postoperatively.


Multiple reddish smooth fragments measuring 1.5 cm in maximum diameter and 5 small black particles measuring 0.3 cm in maximum diameter were embedded in paraffin according to a standard protocol. Routine hematoxylin-eosin staining was performed along with immunohistochemistry using monoclonal antibodies against S-100, Melan-A, HMB45 and MIB-1 on 4 micrometer-thick paraffin sections. The sections were deparaffinized and immunostained using the Benchmark immunohistochemistry staining system (Ventana Medical Systems, Strasbourg, France). The automated protocol is based on an indirect biotin-avidin system. It was optimized for each antibody. Primary antibodies were diluted as follows: AntiS-100 1: Melan-A 1: HMB45 1: MIB-1 1, followed by a universal biotinylated immunoglobulin secondary antibody and diaminobenzidine substrate for visualization. The sections were eventually incubated with a copper enhancer (Ventana) and counterstained with hematoxylin. Negative control slides were processed in parallel with each batch of staining.

Pathological examination revealed a tumor composed by two different tissues, namely areas of compact elongated cells with nuclear palisading and less cellular areas of loose cell arrangement and lipidization. Attached to the tumor, were small fragments of a mass consisted of epithelial-like cells of which the cytoplasm contained abundant melanin pigment granules (Figure 7). The pigmented cells were Melan-A-positive (Figure 8) as well as HMB45-positive (not shown). Both tumors expressed S-100 (not shown). The MIB-1 labeling index was less than 1% in both tumor components.


International Society of Neuropathology