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Pulmonary enteric adenocarcinoma (PEAC), a extremely rare variant of primary invasive adenocarcinoma of the lung, was recognized by the international multidisciplinary classification of lung adenocarcinoma which was proposed by the International Association for the Study of Lung Cancer (IASLC), the American Thoracic Society (ATS), and the European Respiratory Society (ERS) published in early 2011. Histologically, PEAC is considered to be mainly composed of tall columnar cells arranged in an irregular glandular cavity or cribriform pattern with extensive central necrosis which show high resemblance to that of intestinal epithelia and colorectal carcinomas. Immunohistochemically, PEAC can not only expresses typical proteins common to lung primaries but is positive for at least one intestinal markers, such as CDX2, cytokeratin (CK) 20, MUC2, therefore, the differentiation of primary PEACs from metastatic colorectal cancers can be challenging. In this study, we report 9 cases of PEAC and a panel of immunohistochemical protein markers of CK7, CK20, thyroid transcription factor 1 (TTF-1), Napsin A, MUC2 and villin was analyzed with the comparison of 20 metastatic colorectal carcinomas (MCRs), and 20 typical primary adenocarcinomas (tPACs). As was expected, CK7 expression was documented in all 9 PEACs and 20 tPCAs while CK20 was significantly more prevalent in adenocarcinoma that originated from colorectal. Additionally, we evaluate the classical mutations of EGFR, KRAS in the 9 cases of PEACs, it turned out that all tumors were EGFR-wild and KRAS-wild types, which confirmed that PEAC has a separate phenotype from usual pulmonary adenocarcinoma.

Reported herein is a medical curiosities vascular tumor primary arising from the kidney and exhibiting unique histopathological features. A 32-year-old woman underwent a total nephrectomy of right kidney because of a mass localized in the inferior pole. Distinct from other vascular lesions, on histology the tumor had a peculiar composite pattern, consisting of benign and malignant vascular components, which were haphazardly intermixed without any definite margins. The malignant component was composed of epithelioid hemangioendothelioma (45%) and angiosarcoma (50%) with moderate differentiation. Immunohistochemically, the oval to cuboidal to spindle tumor cells expressed only endothelial markers (CD31, CD34 and factor VIII-related antigen). And the angiosarcomatous component was characterized by the presence of a greater proliferation index Ki-67. Unlike other epithelial tumors, smooth muscle actin (SMA), cytokeratin, EMA and S-100 were all negative in the epithelioid tumor cells. These findings led to the diagnosis of a low-grade vascular neoplasm with morphological features consistent with so-called composite hemangioendothelioma (CHE). At 11 month follow up the patient was alive, without evidence of tumor recurrence. CHE is an extremely rare vascular neoplasm, with borderline malignant potential, which mostly occurs in distal extremity of the limbs at the cutaneous level and, only 30 cases have been previously described until now. To our knowledge, this is the first report of CHE arising from the kidney and widens the spectrum of primary vascular tumors arising in the kidney.

In this study, we presented an additional case of renal hemangioblastoma, which demonstrates PAX2 and focal CD10 expression. Histologically, the tumor consisted of sheets of oval or polygonal cells and a prominent vascular network. The tumor cells varied in size, and possessed pale or eosinophilic cytoplasm that sometimes contained sharply delineated fine vacuoles. The tumor cell nuclei with inconspicuous nucleoli showed moderate nuclear atypia and pleomorphism. Focal areas of stromal hyalinization and sclerosis were detected. On account of its strong or moderate immunoreactivity for the a-inhibin, S100, NSE, and EGFR, the diagnosis of renal hemangioblastoma was established. For further evidence of VHL deficiency, the tumor was subjected to VHL sequence analysis of all three exons and fluorescence in situ hybridization (FISH) detection for chromosome 3p deletion. None of the VHL gene mutations and chromosome 3p deletion was detected in the tumor. Because of several shared morphological and immunophenotypic features, renal hemangioblastoma may be underrecognized and should be included in the differential diagnosis of primary renal tumors, in particular clear cell renal cell carcinoma. The unexpected positive staining of PAX2 and CD10 in renal hemangioblastoma should be particular concerned. Using a combination of immunoprofile may be helpful to the differential diagnosis of these renal tumors.

Papillary renal cell carcinoma (PRCC) is traditionally classified into type 1 and type 2. Recently, an oncocytic variant of PRCC has been described. We report a series of 6 oncocytic renal papillary tumors (OPRCC) which tended to occur in older patients (mean, 56.8 years) with a male preference (male-to-female ratio is 5:1). All 6 patients are alive with no evidence of disease after initial resection, showing an indolent clinical behavior. Histologically, tumors exhibited predominant papillary structure with delicate fibrovascular cores. Papillae were lined by single layers of cells with large, deeply eosinophilic and finely granular cytoplasms and round regular nucleus. The phagocytosis of tumor cells was frequently and evidently seen in our cases that hemosiderin-laden tumor cells and foamy tumor cells were noticed in five and four cases respectively. All tumors were immunoreactive for racemase, vimentin, CD10, and MET and negative for CD117. While E-cadherin, EMA, and cytokeratin 7 exhibited variable immunopositivity. FISH analysis was performed in five of six cases and found heterogeneous results. Trisomy of chromosomes 7 was found in three cases and trisomy of chromosomes 17 in two cases. Loss of chromosome Y was noted in one of four tumors in male patients. MET gene status was also investigated by direct sequencing in all 6 cases and found no distinct mutation in any case. These results suggest that OPRCC shows distinct morphology, indolent clinical behavior, and similar immunohistochemical and cytogenetic features with PRCC, seems to be a variant in the PRCC group. Whether the strong expression of MET indicates a potential therapeutic target is still unknown and requires further investigation in clinical trials.