High Wilms' tumour gene (WT1) expression and low mitotic count are independent predictors of survival in diffuse peritoneal mesothelioma.

AIMS: To evaluate the use of the Wilms' tumour gene (WT1) marker and histomorphological parameters as indicators of prognosis in malignant peritoneal mesothelioma (MPM). METHODS AND RESULTS: Histological samples of 31 MPM were stained immunohistochemically for the WT1 protein. The results were quantified by recording the number of stained nuclei, and then correlated with patient survival. Statistical correlation was evaluated for tumour histotype, mitotic count (MC), nuclear grade (NG), necrosis, lymphoid response (grade of inflammation) and desmoplasia with regard to survival. High-grade histology (solid epithelioid, pure sarcomatoid or biphasic tumours), high NG, MC more than five per 10 per high-power field (HPF), necrosis and desmoplasia were associated with a significantly worse prognosis. Patients with MPM with low WT1 expression (≤25% of positive cells) survived for a significantly shorter time compared to those with high WT1 expression (>25% of positive cells) (P = 0.0001). The 50% survival time of subjects with low WT1 expression was 2.9 months [95% confidence interval (CI): 2.05-3.71] versus 31.5 months (95% CI: 20.4-42.5) for those with high WT1 expression. On multivariate analysis, WT1 and MC were found to be associated independently with survival (P = 0.002; P = 0.005, respectively). CONCLUSIONS: Our study suggests that low WT1 expression and high MC may be indicative of an unfavourable prognosis in patients with advanced malignant peritoneal mesothelioma.

Low-grade fibromyxoid sarcoma of the medial vastus: a case report.

Low-grade fibromyxoid sarcoma (LGFMS) was first described by Evans in 1987, and since then, just over 150 cases have been reported, showing the rarity of this tumor. We report the clinical case of a 56-year-old man with a swelling on the distal third of the left thigh. The mass had grown in the course of 1 year and was surgically excised, obtaining complete resolution. Immuno-histological examination demonstrated the lesion to be a LGFMS, defined as a benign tumor but with a high incidence of local and distant recurrence (5-10%). At 2-year follow-up the patient was disease-free, confirming the efficacy of the surgical excision. In literature, the frequency of incomplete excision of LGFMS due to inappropriate diagnosis is stressed. It is this element that contributes most to the high rate of recurrence. We recommend that the eventuality of observing this rare tumor be borne in mind, and that care be taken to perform a complete, ample excision.