Imaging methods are important for characterizing the lesions, and they may suggest the diagnosis. However, definitive diagnosis is obtained by biopsy or pathological analysis of the operative specimen.

On radiologic evaluation, 10x8x7 cm multiloculated cystic mass with small solid areas and septae in the lateral surface of the upper arm was showed on the ultrasonography and magnetic resonance imaging. In addition, a fluid–fluid level indicating hemorrhage was present within a largest cystic area on T2-weighted sequences. T1-weighted images after administration of Gd-DTPA showed marked enhancement at the solid components and septae.

Technetium-99m methylene diphosphonate bone scan was performed. An increased blood flow around of the large hypoactive areas was seen in the second phase of the bone scan (fig. 1). The delayed image showed significant irregular activity accumulation in the lesion on bone scan (fig. 2).

Figure 1: An increased blood flow around of the large hypoactive areas was seen in the second phase of the bone scan.

Figure 2: The delayed image showed significant irregular activity accumulation in the lesion on bone scan (fig. 2).

Surgical exploration disclosed an encapsulated mass arising from a musculocutaneus nerve. Histopathologically the spindle cells are arranged in short bundles or interlacing fascicles. In some areas there was whorling of the cells. Scattered atypical cells were seen. There was neither mitosis nor anaplasia. The schwann cells were expressing invariably strong, diffuse immunreactivity for S-100 protein and vimentin (fig 3 and 4). Staining for alpha smooth muscle actin and desmin was not observed. According to these findings, the case was reported as an ancient schwannoma.

Figure 3: An H & E-stained section shows spindle cells arranged in bundles and whorls with alternating loosely textured areas. (hematoxylin-eosin, original magnification ×200) (fig. 3).

Figure 4: Immunoperoxidase staining for S-100 protein shows intense diffuse cytoplasmic and nuclear positivity. Note the fascicular arrangement of cells with scattered atypical nuclei. (immunohistochemistry S-100, original magnification ×400) (fig. 4).

The differential diagnosis of peripheral nerve schwannomas include neurofibroma, malignant peripheral nerve sheath tumor, leiomyoma, lymphadenopathy, vascular anomalies, lipomas, angiomas and dermal nerve sheath myoma ^2,6.

Ultrasonography, magnetic resonance and computed tomography were enabled the correct diagnosis of schwannoma. But differential diagnosis of these tumors by imaging modalities can be difficult ^6,7. Nuclear medicine may be help for differential diagnosis and distinguish benign schwannoma from malignancy. Previous authors reported that schwannoma could be demonstrated with increased Tc-99m- (V) DMSA ⁸, F-18-FDG ⁹, Tl-201 ¹⁰, I-131-MIBG ¹¹, Tc-99m-diphosphonates ¹² activity accumulation but did not uptake Ga-67 ⁸ and Indium-111 octreotide ⁷.

In conclusion, surgeons should have a current knowledge of the diagnostic possibilities and the treatment options about peripheral nerve tumors such as schwannomas. The ancient schwannoma can be demonstrated with the bone scintigraphy.