Primary retroperitoneal serous adenocarcinoma (PRSA) is an extremely rare malignancy, with only seven cases having been previously reported. We report a case of PRSA in a 42-year-old woman treated with surgical resection and adjuvant chemotherapy. The histopathological findings of PRSA resemble those of ovarian serous carcinoma, which indicates that a combination of complete surgical resection with adjuvant chemotherapy may be the best treatment option for PRSA.

Aims Gastric cancer (GC) is one of the leading causes of cancer‐related death worldwide. Genes expressed only in cancer tissue may be useful biomarkers for cancer diagnosis and therapeutics. The aims of the present study were to analyse regulator of calcineurin 2 (RCAN2) in a large number of GCs, and to investigate how these expression patterns correlate with clinicopathological parameters and various markers. Methods and results An immunohistochemical analysis of RCAN2 in 207 GC tissue samples showed that 110 (53%) GCs were positive for RCAN2. RCAN2‐positive GCs were more advanced in terms of TNM classification and tumour stage than RCAN2‐negative GCs. Furthermore, RCAN2 was an independent prognostic classifier for GC patients. The cell growth and invasiveness of RCAN2 small interfering RNA (siRNA)‐transfected GC cell lines were less than those of the negative control siRNA‐transfected cell lines, whereas those of RCAN2‐transfected cells were significantly increased as compared with those of empty vector‐transfected cells. RCAN2 siRNA inhibits the phosphorylation of AKT and p44/p42 (ERK1/2). RCAN2 was colocalised with EGFR, nuclear β‐catenin, MMP7, laminin‐γ2, VEGF‐A, and VEGF‐C. Conclusion These results suggest that RCAN2 is involved in tumour progression and is an independent prognostic classifier in patients with GC.

Balloon cell malignant melanoma (BCMM) is a very rare malignant melanoma subtype. The clinical appearance of BCMM varies; it may be nodular, ulcerated, polypoid, papillomatous and often non-pigmented. The tumor cells histologically appear large, polygonal or round and contain abundant granular or vacuolated cytoplasm. We herein report the case of a 32-year-old female who presented with a focal eccentric pigmented mass in the left lumbar region of 15 mm in diameter that had been present for several years. She underwent tumor excision. The histopathological analysis showed epithelioid melanocytes with clear cytoplasm. An immunohistochemical analysis revealed that the cells were positive for HMB-45 and S-100 protein and negative for cytokeratin. The balloon cell component stained negative for Fontana-Masson. A month later, the patient underwent excision of the bilateral inguinal lymph nodes and metastatic BCMM was revealed. The lymph node metastases showed the complete replacement of lymph nodes by balloon cells. A diagnosis of BCMM (Breslow depth 10 mm, Clark level V) without ulcer was rendered. Staining with Ki-67 was positive in almost 44% of the balloon cells.

Invasive micropapillary carcinoma (IMPC), an aggressive variant of adenocarcinoma, is associated with a poor prognosis. Although IMPC has been reported to occur in various organs, pure IMPC has only been reported in the breast, pancreas and colon. There are no reports of IMPC of the esophagogastric junction (EGJ). According to previous reports on gastric IMPC, IMPC occupied, at most, 90 % of the whole tumor. IMPC is reported to occur least frequently in the gastric cardia. We herein report a rare case of pure IMPC of the EGJ. A 71-year-old male patient presented with epigastric distress. Gastric endoscopy demonstrated an irregularly-elevated lesion of 50 mm in diameter at the EGJ. The patient underwent proximal gastrectomy, resection of the regional lymph nodes and a punch biopsy of the liver. A histopathological examination revealed that almost all of the regions, including the lymph nodes and the sites of liver metastasis, contained IMPC and that a minute region (<1 % of the whole cancer) contained tubular or papillary adenocarcinoma. The further accumulation of pure IMPC cases like the present case would help to elucidate its pathogenesis.

Epithelial-myoepithelial carcinoma (EMC) is a rare salivary gland tumor with a low-grade malignancy, and EMC with high-grade histopathological features is exceedingly rare. Furthermore, EMC with intracellular mucin is also extremely rare. We report an uncommon case of a high-grade EMC of the parotid gland with mucous cell differentiation in a 66-year old Japanese woman who noticed a right palpable parotid mass increasing in size within a one-year period. The cytological specimen showed a focally biphasic structure and included isolated or discohesive piled-up clusters with hyaline globules surrounded by neoplastic cells with nuclear atypia. The gross examination revealed a relatively well-demarcated, multinodular gray-whitish and solid mass. Histologically, the tumor consisted of variably sized solid nests or trabeculae with central necrosis and increased mitotic activity, and invaded into adjacent skeletal muscles. Immunohistochemically, the biphasic ductal and myoepithelial differentiation of this tumor confirmed the diagnosis of high-grade EMC. Furthermore, numerous small nests with d-PAS and alcian blue-positive mucous cells predominated in about 5% of the whole tumor, and these mucous cells were encompassed by neoplastic myoepithelial cells. We should recognize this variant of EMC because we can't rule out the possibility of EMC even in the presence of mucous cells.