Diffuse malignant mesothelioma of the peritoneum is a rare diagnosis. Despite many histopathologic similarities between peritoneal and pleural tumors, clinical and prognostic features may be quite different. There is a paucity of data evaluating molecular features of peritoneal mesotheliomas. Therefore, we compared the results of a battery of immunohistochemical markers, some with therapeutic implications, in patients with primary peritoneal or pleural mesotheliomas. We examined 24 peritoneal and nine pleural malignant mesotheliomas with a battery of immunohistochemical markers (cytokeratin AE1/3, calretinin, c-kit/CD117, desmin, epidermal growth factor receptor (EGFR), estrogen receptors (ER), progesterone receptors (PR), MIB-1, and cleaved caspase-3) in an attempt to distinguish any differences in this tumor arising in these two distinct locations. The results indicate that the only marker to show a significant difference in its staining pattern between these two sites was EGFR (P ¼ 0.0004). In all, 92% (22/24) of peritoneal tumors demonstrated 3 þ or 4 þ immunoreactivity with EGFR, opposed to only 33% (3/9) pleural tumors. There was no significant difference in immunoreactivity between the pleural and peritoneal tumors with c-kit, ER, PR, cleaved caspase 3, calretinin, and desmin. There was a trend toward increased cytokeratin (P ¼ 0.07) and MIB-1 (P ¼ 0.08) expression in the peritoneal group. There was no significant difference in age, sex, or histologic subtype between the two locations. In conclusion, despite similarities between peritoneal and pleural mesothelioma, there are differences between this neoplasm arising in these two sites. The EGFR expression is more pronounced in peritoneal tumors compared to pleural tumors. The increased expression of EGFR in the peritoneal lesions may be of clinical significance with the recent emergence of epidermal growth factor receptor-targeted therapies.

We describe a patient with granulomatous mastitis due to Mycobacterium abscessus that presented as a mass lesion and was associated with a pierced nipple. To our knowledge, this is the first reported case of mastitis due to M. abscessus and the first association of this organism with body piercing.

The sinonasal region is the site of several hamartomatous lesions, the majority of which are mesenchymal, with vascular hamartomas predominating. The occurrence of hamartomas in the nasal cavity of infants and children is especially rare. Nasal chondromesenchymal hamartoma (NCMH) is a rare lesion of the intranasal sinuses generally diagnosed in the newborn period, with the eldest reported patient presenting at 16 years of age. This neoplasm is composed of mesenchymal-stromal and chondroid tissue in varying proportions. It is felt to be analogous to the mesenchymal hamartoma of the chest wall, a lesion of similar histology generally involving the ribs and chest wall of neonates. To the best of our knowledge, only 14 cases of NCMH have been reported to date. We report a case of NCMH in an 11-year-old boy.

Gastrointestinal stromal tumors are a heterogeneous group of neoplasms that have clinical and histologic features that vary depending on their location within the gastrointestinal tract. Prediction of clinical behavior in this group of tumors is notoriously difficult, and the same criteria for malignancy do not necessarily apply to stromal tumors from different sites within the gastrointestinal tract. Using known clinical behavior with long-term follow-up, we attempted to determine which features, if any, are associated with clinical behavior in stromal tumors arising in the stomach, the most common site for such tumors. Seventy-seven gastric stromal tumors were studied and classified as "adverse outcome (AO) tumors" (malignant) or "nonadverse outcome tumors" (benign) based on their known clinical outcome. AO was defined as metastasis and/or death due to tumor. Patients with a non-AO had at least 5 years of tumor/metastasis-free follow-up. Thirty-seven patients had an AO (follow-up [metastasis at presentation] 0-73 months; median 6 months), and 40 patients had a non-AO (follow-up 60-264 months; median 84 months). All cases were reviewed by two authors (J.R.G., H.D.A.), who were blinded to clinical outcome and gross features, and classified as histologically benign or not benign using preset, defined histologic criteria based upon the authors' prior experience with a large number of these tumors. If the tumor did not fit with either the characteristic cellular spindle cell or benign epithelioid cell patterns, the tumor was classified as not benign. Clinical outcome was then correlated with the histologic designation to determine if these preset criteria were valid. The authors were able to accurately classify the tumors as benign or not benign with a sensitivity of 100% and a specificity of 92%. In addition, for all cases individual morphologic and clinical features were examined. Features associated with an AO included tumor size >/=7 cm, high cellularity, mucosal invasion, high nuclear grade, mitotic counts >/=5/50 high power fields, mixed cell type, and the presence of a myxoid background and/or absence of stromal hyalinization. By recognizing several well-defined patterns of benign gastric stromal tumors and the myriad of individual features shown to correlate with an AO, one can better predict the clinical behavior of gastric stromal tumors.