Epithelioid Haemangioendothelioma of the Gastric Wall with Unique Histomorphology: A Case Report
This case report describes a rare primary gastric epithelioid haemangioendothelioma in a 64-year-old man, diagnosed through histomorphology and a distinctive immunohistochemical profile (TFE3-positive, CAMTA1-negative) that suggested a YAP1-TFE3 rearrangement, thereby emphasizing the importance of specific markers in identifying this rare vascular neoplasm when molecular testing is unavailable.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Inside the human body, blood vessels are not merely passive pipes; they are living structures built from specialized cells that line the interior of every vessel. Sometimes, these cells grow out of control, forming tumors. Most of these growths are common and well-understood, but a tiny fraction are so unusual that they challenge even experienced doctors. One such rare growth is called epithelioid hemangioendothelioma. It is a type of cancer that starts in the lining of blood vessels, but it behaves in a way that sits somewhere between a harmless lump and an aggressive malignancy. Because it is so rare, especially when it appears in the stomach, doctors often struggle to identify it correctly. They must distinguish it from other tumors that look similar under a microscope but require completely different treatments. Understanding these rare cases is vital because it helps physicians recognize the disease earlier and choose the right path for healing.
In a recent report, a team of doctors and researchers described a unique instance of this rare tumor found in a 64-year-old man. The man had no symptoms and felt perfectly healthy when he underwent a routine scan of his abdomen for an unrelated reason. The scan, a detailed X-ray that uses contrast dye to highlight internal structures, revealed a small, round mass attached to the outer surface of his stomach. The mass was tiny, measuring just 18 by 19 by 14.5 millimeters, and it appeared to be well-defined, meaning it had clear borders and did not seem to be invading the surrounding tissue. Because the man had no pain or digestive issues, the doctors decided to remove the mass surgically using a minimally invasive technique, allowing for a quick recovery.
Once the tissue was removed, it was sent to a laboratory for a close look under a microscope. The initial examination showed a mix of cell types. Some cells were round and plump with pinkish interiors, while others were stretched out and spindle-shaped. These cells were embedded in a stiff, glassy material that looked like a dense, fibrous jelly. The cells contained small empty spaces inside them, a feature that sometimes hints at a blood vessel origin. The doctors also checked the cells for specific proteins that act like name tags, helping to identify what kind of tissue they came from. The cells did not have the markers for common stomach cancers, nerve tumors, or muscle tumors. However, they did show strong signs of being blood vessel cells. Based on these clues, the team initially thought it was a low-grade tumor of the connective tissue, but they knew they needed more information to be certain.
To solve the mystery, the case was sent to a specialist center for further testing. The researchers performed additional chemical staining on the tissue to look for specific proteins that act as genetic switches. They found that the cells were full of a protein called TFE3, which appeared as a bright signal in the nucleus of the cells. At the same time, the cells were completely negative for another protein called CAMTA1. This specific pattern—strong TFE3 and no CAMTA1—is a rare signature. It suggests that the tumor was driven by a specific genetic rearrangement, where two parts of the cell's instruction manual had swapped places. This particular swap, involving the TFE3 gene, is known to cause a specific subtype of epithelioid hemangioendothelioma. While the team did not perform a full genetic sequencing test to confirm the swap at the DNA level, the combination of the cell's appearance and this unique protein profile provided a very strong indication of the diagnosis.
The final diagnosis was a primary epithelioid hemangioendothelioma of the stomach wall, specifically the rare subtype driven by the TFE3 gene rearrangement. This finding is significant because it confirms that even in a place where this tumor is almost never seen, it can still occur. The patient recovered well from the surgery and has not shown any signs of the tumor returning. This case serves as an important reminder for medical professionals that when they see a strange growth in the stomach, they should consider this rare possibility. By using specific protein tests to look for TFE3 and CAMTA1, doctors can guide their diagnosis even when advanced genetic testing is not immediately available, ensuring that patients receive the correct care for these uncommon and complex conditions.
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