<b>Clinicopathological significance of gastric poorly differentiated medullary car</b><b>cinoma </b>

Abstract

Poorly differentiated gastric adenocarcinoma of solid type is known to show a clinicopathological diversity, but its morphological characteristics have rarely been investigated. In this study, we defined poorly differentiated medullary carcinoma indicating the following three characteristics: (i) more than 90% of the entire tumor were composed of poorly differentiated adenocarcinoma in a medullary growth, (ii) the tumor exhibited an expansive growth at the tumor margin, and (iii) special types such as an α-fetoprotein-producing carcinoma, neuroendocrine carcinoma, and carcinoma with lymphoid stroma were excluded. Based on the definition, we subclassified the poorly differentiated gastric adenocarcinoma of solid type into the two groups: medullary carcinoma and non-medullary carcinoma, and clinicopathologically analyzed 23 cases of medullary carcinomas and 38 cases of non-medullary carcinomas. The medullary carcinomas less frequently displayed lymphatic invasion, venous invasion, and lymph node metastasis, compared with the non-medullary carcinoma (P < 0.001, P = 0.002, and P < 0.001, respectively). The patients with medullary carcinomas significantly showed better disease-free survival (P = 0.017). This is the first study to demonstrate that poorly differentiated adenocarcinoma of solid type can be subclassified into tumors with low and high malignant potentials. Gastric poorly differentiated medullary carcinoma is considered to be a novel histological type predicting good patients' prognosis.

Solid-type poorly differentiated adenocarcinoma of the stomach: clinicopathological and molecular characteristics and histogenesis

“…Thus, morphology, MSI, and biological behavior in solid-type PDA are different from those in non-solid-type PDAs. There have only been a few pathological reports until now, and the details regarding solid-type PDA of the stomach remain obscure [4,[10][11][12][13][14].…”

Gastric Medullary Carcinoma with Sporadic Mismatch Repair Deficiency and a TP53 R273C Mutation: An Unusual Case with Wild-Type BRAF

“…Gastric medullary carcinoma, a new WHO diagnostic entity, is a very rare subtype of gastric cancer that is histologically characterized by a sharply demarcated, poorly differentiated carcinoma with organoid/syncytial growth pattern with pushing borders and an associated lymphocytic inflammatory response [ 1 , 7 ]. It is typically seen in elderly men, associated with MSI-H, presents at an early clinical and pathologic stage, and has an improved prognosis compared to gastric cancers of other special types [ 6 ].…”

“…Despite the synonymous determination by the WHO, gastric medullary carcinoma is frequently associated with microsatellite instability-high (MSI-H), while lymphoepithelioma-like carcinoma is associated with Epstein Barr Virus (EBV) infection [ 4 – 6 ]. Gastric medullary carcinoma has been defined histologically as comprising more than 90% of poorly differentiated solid type adenocarcinoma with associated lymphocytic infiltrate, demonstrating pushing growth pattern at the tumor edge, and excluding other special types of gastric carcinoma [ 7 ].…”

Solid‐type poorly differentiated adenocarcinoma of the stomach: Deficiency of mismatch repair and SWI/SNF complex

“…Gastric cancer remains the third leading cause of cancer death worldwide. Although it is commonly supposed that PDA has a worse prognosis than other histological types, several studies showed that PDA with solid morphology is associated with a favorable prognosis despite its poorly differentiated histology . According to the Japanese classification, PDAs are divided into the solid‐type and nonsolid‐type…”

“…Although it is commonly supposed that PDA has a worse prognosis than other histological types, several studies showed that PDA with solid morphology is associated with a favorable prognosis despite its poorly differentiated histology. [1][2][3][4] According to the Japanese classification, PDAs are divided into the solid-type and nonsolid-type. 5 Solid-type PDAs often contain a glandular component that tends to be detected superficially in the tumor, suggesting that solid-type PDAs develop from a tubular or papillary adenocarcinoma.…”