p53 expression in gastrointestinal stromal tumors.

The understanding of gastrointestinal stromal tumors (GIST) is complex because of their divergent differentiation and unpredictable behavior. However, our understanding is becoming clearer, despite some cases of tumors which are exceptions from the typical cases. Tumor size, mitotic rate and, to a lesser degree, location, are the most important predictive parameters for the behavior of GIST. In this study, expression of p53 protein was evaluated in 15 cases of GIST. Tumors were divided into three groups: (i) benign (mitotic index [MI] < 5/50 high-power fields [HPF] and size < 5 cm); (ii) borderline (MI < 5/50 HPF and size > or = 5 cm); and (iii) malignant (MI > or = 5/50 HPF, irrespective of size). The mean values of p53 expression in the three groups were significantly different (benign, 10.6%; borderline, 33.8%; and malignant, 71%). The conclusion of the present study is that p53 overexpression correlates well with the malignant potential of GIST.

Granulosa cell tumor of the adult type: a case report and review of the literature of a very rare testicular tumor.

We report a case of testicular granulosa cell tumor of the adult type in a 48-year-old man. Microscopically, the tumor consisted of round to ovoid cells with grooved nuclei that were arranged in several patterns, including microfollicular, macrofollicular, insular, trabecular, gyriform, solid, and pseudosarcomatous. These cells demonstrated strong immunopositivity with MIC2 (O13) antibody, vimentin, and smooth muscle actin and focal positivity with cytokeratin. Although this type of sex cord-stromal tumor is relatively common in the ovaries, it is still extremely unusual in the testis, and it probably represents the rarest type of testicular sex cord-stromal tumor.

p53 and Bcl-2 oncoprotein expression in placentas with hydropic changes and partial and complete moles.

Forty molar and non-molar placentas with hydropic changes (14 complete moles, 14 partial moles, and 12 hydropic non-molar placentas) were examined immunohistochemically for expression of oncoproteins p53 and Bcl-2. The data were evaluated to determine if p53 and Bcl-2 expression could aid in differentiating molar from non-molar pregnancies on the one hand and complete mole from partial mole on the other. Thirteen out of fourteen complete moles showed p53 expression (93%), 8 of the 14 partial moles expressed p53 (57%), and none of the non-molar pregnancies expressed p53 in the extravillous intermediate trophoblasts. Regarding Bcl-2, the syncytiotrophoblasts of most molar and non-molar placentas showed strong and diffuse positivity. These results suggest that p53 expression can be used as a distinguishing parameter between complete moles and placentas with hydropic changes on the one hand and to a lesser extent between partial moles and placentas with hydropic changes on the other hand. Bcl-2 cannot be used in the same way as p53.

Malignant peritoneal mesothelioma.

Malignant peritoneal mesotheliomas are rare tumors arising from the peritoneal surface. We report a 53 year old, non-asbestos exposed Saudi male who presented with exudative ascites. The diagnosis was obtained from laparoscopic biopsy. To the best of our knowledge this entity has not been described in the Saudi community. The aim is to increase the awareness among the medical community about this rare entity.

Spindle cell carcinoma of the breast, a mimicker of benign lesions: case report and review of the literature.

The clinical and pathologic features of a breast tumor with unusual morphology in a 69-year-old woman are presented. Spindle cell carcinoma is considered one of the variants of metaplastic carcinoma and is commonly described in the upper aerodigestive tract, but it is relatively rare in the breast. This case is uniquely different from the usual cases of spindle cell carcinoma because of the lack of squamous differentiation or a recognizable infiltrating ductal component at the light microscopic level. With immunohistochemical stains using keratin and actin, a rather prominent network of infiltrating compressed ductal structures became apparent. These immunohistochemical features are consistent with the current concept of myoepithelial origin for metaplastic carcinomas. Although mention has been made in the literature of cases in which this "bland" carcinoma could be confused with benign nonneoplastic conditions, few illustrated examples exist. The prognosis for this particular subgroup of metaplastic carcinoma may be somewhat better than that for ordinary ductal carcinoma. For prognostic purposes, this entity should be distinguished from other metaplastic carcinomas and sarcomas, but more importantly, it should be differentiated from lesions such as nodular fasciitis, reactive granulation tissue, and fibromatosis, with which it may be confused histologically.