A mosaic PIK3CA variant in a young adult with diffuse gastric cancer: case report

Hereditary diffuse gastric cancer (HDGC) is associated with germline deleterious variants in CDH1 and CTNNA1. The majority of HDGC-suspected patients are still genetically unresolved, raising the need for identification of novel HDGC predisposing genes. Under the collaborative environment of the SOLVE-RD consortium, re-analysis of whole-exome sequencing data from unresolved gastric cancer cases (n = 83) identified a mosaic missense variant in PIK3CA in a 25-year-old female with diffuse gastric cancer (DGC) without familial history for cancer. The variant, c.3140A>G p.(His1047Arg), a known cancer-related somatic hotspot, was present at a low variant allele frequency (18%) in leukocyte-derived DNA. Somatic variants in PIK3CA are usually associated with overgrowth, a phenotype that was not observed in this patient. This report highlights mosaicism as a potential, and understudied, mechanism in the etiology of DGC.

Gastric Cancer Case with Skin Metastases and Scleroderma-like Paraneoplastic Rheumatic Syndrome

In this case report, we will describe a gastric cancer case, which presented with rare manifestation of skin metastases and unrelated to the mechanical impact of distant metastases scleroderma-like paraneoplastic rheumatic syndrome. 72-year-old woman was referred to hospital with complaints gradual during the time period of one year. Skin changes included - thickening, dermal induration mostly seen on her upper body – arms, neck, face, chest and abdominal wall, causing contracture and limited movements. In the area of her upper arms, neck and upper part of her chest multiple small, painless, hard subcutaneous nodules were present and hyperpigmentation in the neck area. There were no signs of Raynaud’s phenomenon, telangiectasia, alopecia, hypopigmentation or muscle weakness and pain. Upon further examination and multiple biopsies (gastric and skin nodules) poorly differentiated gastric carcinoma was confirmed with peritoneal dissemination, ascites, cutaneous, subcutaneous metastasis and scleroderma-like paraneoplastic syndrome. After systemic treatment for gastric cancer patient showed improvement of paraneoplastic syndrome manifestations, quality of life and radiologically stable disease.