P4209 - Perivascular Epithelioid Cell Tumor (PEComa) in an Adolescent Patient: A Rare Case of Misdiagnosis

Oleksandr Shumeiko, MD¹, Yaroslav Dombrovsky, MD^2
1University of Cincinnati Medical Center, Cincinnati, OH; ²Medical Laboratory CSD Health Care, Kyiv, Kyyiv, Ukraine

Introduction: PEComa is a mesenchymal neoplasm composed of distinctive epithelioid cells with variable expression of smooth muscle and melanocytic markers. Gastrointestinal stromal tumors (GISTs) and PEComas share overlapping histological features, making accurate diagnosis challenging, especially in young patients.

Case Description/Methods: Case Presentation: We present a case of a 13-year-old female patient who underwent surgery for GIST, which was subsequently found to be a misdiagnosis. The patient presented with symptoms of abdominal pain and underwent a gastric resection procedure. The postoperative histopathological evaluation revealed a perivascular epithelioid cell tumor in the gastric wall.

Methods: The resected gastric specimen was examined microscopically, and immunohistochemistry staining was performed. The tumor cells were positive for HMB-45 and α-SMA markers, while SOX-10 staining was negative, confirming the diagnosis of perivascular epithelioid cell neoplasm (PEComa).

Results: Microscopically, the tumor exhibited nested and trabecular growth patterns with epithelioid cells displaying abundant light and eosinophilic cytoplasm. The presence of focal pleomorphism and low mitotic activity (0.2 mitoses per 2.0 mm^2) were observed. These findings supported the diagnosis of a benign PEComa.

Discussion: Conclusion: PEComas are rare neoplasms, especially in the gastrointestinal tract, and their diagnosis can be challenging due to overlapping features with other tumors, such as GISTs. In this case, a 13-year-old female patient initially underwent gastric resection for a suspected GIST, but the postoperative evaluation revealed a PEComa. Accurate diagnosis of PEComa is essential for appropriate management and follow-up, as the behavior and prognosis may vary. Clinicians should consider PEComa as a differential diagnosis in young patients with gastric masses to ensure optimal treatment strategies.


Disclosures:


Oleksandr Shumeiko, MD¹, Yaroslav Dombrovsky, MD². P4209 - Perivascular Epithelioid Cell Tumor (PEComa) in an Adolescent Patient: A Rare Case of Misdiagnosis, ACG 2023 Annual Scientific Meeting Abstracts. Vancouver, BC, Canada: American College of Gastroenterology.