Herein is described a unique case of esophageal cancer mimicking acantholytic squamous cell carcinoma (SCC). The patient succumbed to the disease within one month of diagnosis. Autopsy revealed a 10-cm esophageal tumor, characterized by prominent acantholysis-like areas composed of discohesive cancer cells, along with nested growth of SCC. These discohesive cancer cells focally exhibited pagetoid extension into adjacent esophageal epithelium, comprised ~60% of the esophageal tumor volume and had widely metastasized to the lungs, chest wall, liver, spleen, right adrenal gland, bones and lymph nodes. No metastases of SCC were observed. SCC cells were immunohistochemically positive for keratin 5/6 and E-cadherin and were negative for mucin and carcinoembryonic antigen (CEA). However, the discohesive cancer cells exhibited negativity for keratin 5/6, positivity for mucin and CEA, and diminished or no immunostaining for E-cadherin. Thus, these discohesive cells represented true adenocarcinomatous differentiation rather than acantholytic SCC cells. It was concluded that this tumor was an esophageal adenosquamous carcinoma with 'pseudo'-acantholytic adenocarcinoma components, which should be considered as a rare but distinctive type of aggressive cancer.

Lipomembranous fat necrosis (LFN) is an uncommon but distinct form of fat necrosis, which is characterized by eosinophilic, crenulated and/or serpiginous membranes. LFN exhibits macrocystic, microcystic and/or crushed features. LFN is routinely detectable on hematoxylin and eosin (H&E)-stained sections, and is present both in the acute phase and in the later or fibrous stage of necrotic fatty lesions. Smaller crushed LFN embedded within fibrous tissues may be difficult to recognize on H&E-stained sections, but can be highlighted by some staining techniques, including Masson trichrome, periodic acid-Schiff, orcein, long Ziehl-Neelsen stain, silver impregnation, phosphotungstic acid-hematoxylin and luxol fast blue staining. LFN was initially considered a specific feature of Nasu-Hakola disease, but has since been identified in various subcutaneous or intraabdominal lesions related to ischemic conditions or venous insufficiency. In addition, LFN is detectable in intra-articular loose bodies and aortic valves with or without dysfunction, suggesting that LFN is also associated with ischemia-like hypoxic conditions or malnutrition. LFN is considered to be a histological hallmark of hidden ischemic or hypoxic/malnourished conditions in various diseases; however, the exact mechanisms of LFN remain poorly understood. The present review described the clinicopathological features of this interesting, but poorly characterized, condition.

Abstract. To elucidate the frequency and histopathological features of gastrointestinal (GI) tract-like muscular walls developing in ovarian mature cystic teratoma (MCT), the present study examined 149 MCTs surgically removed from 126 females, including 23 bilateral cases. GI tract-like muscular walls were identified in 9 (7.1%) cases, and were accompanied by mucosa in 5 cases, muscularis mucosae in 5 cases, serosa in 5 cases and all of these components in 3 cases. The mean size of the GI tract-like structures was 0.6 cm. The presence of MCT-related GI tract-like muscular walls was not significantly associated with patient age, size of MCTs or bilateral presence of MCT. The detected mucosae and muscular walls commonly demonstrated incomplete or anomalous features. Immunohistochemically, a few weakly KIT + spindle and/or stellate cells were identified in 7 cases (77.8% of the 9 cases of MCT-related GI tracts); these cells were presented chiefly near conspicuous or inconspicuous S-100 protein + neural tissues between the conspicuous or inconspicuous two muscular wall layers, indicating interstitial cells of Cajal (ICCs). Discovered on gastrointestinal stromal tumors 1 co-expression in KIT + ICCs was observed in only 1 case. Neural cell-related intramuscular cluster of differentiation 34 + cells were occasionally observed; however, no hyperplastic ICCs were observed in the present study.