Pathological findings
Macroscopically, the resected huge solitary mesenteric tumour, which measured 30x23x16.7cm and weighed 6500 grams, was well-circumscribed and multinodular which appeared as a firm mass with a pinkish outer surface. The cut surface was solid and pale yellowish-brown and showed areas of necrosis (Figure 1).
Microscopically, the sections through the tumour mass show a highly cellular tumour, characterized by spindle cells arranged in a storiform pattern, and in areas in palisaded forms. There are other areas exhibiting a herring-bone type pattern of arrangement. The cells are spindle shaped, with markedly vesicular nuclei, and coarse chromatin pattern, with many areas of palisaded necrosis(Figure 2,3 and 8). Mitoses are readily seen, and in areas, nuclear pleomorphism with tumour giant cell formation is prominent (Figure 4 and 5). Abnormal and bizarre mitoses are observed. There is no evidence of pigmentation, osseous or chondroid differentiation. The surgical margins are involved by the malignant cells.
The tumour cells stained diffusely and strongly for STAT-6 (Figure 9), bcl-2 (Figure 10) and CD34 (Figure 11). Staining for CD117, DOG-1, S-100, Desmin, EMA and TLE-1 were negative. About 15% of cells show MIB-1 activity.
*(To scan gross picture in JPEG)
Figure 1: The cut surface of the extrapleural (retroperitoneum) malignant solitary fibrous tumour showed multinodular pale yellowish-brown solid appearance with areas of necrosis