Presentation
Abdominal pain. History of ascariasis.
Patient Data
A large heterogeneous right upper quadrant soft tissue mass lesion is seen insinuated between the gastric antrum/duodenum and the gallbladder and appears inseparable from the gallbladder. It shows a heterogeneous appearance with internal hyperdense areas on the non-contrast images denoting hemorrhage and heterogenous post-contrast enhancement. The gallbladder is infiltrated and is also distended by internal similar soft-tissue masses. The mass compresses the gastric antrum and duodenum.
Surrounding multiple mesenteric lymph nodes are noted.
Pathology revealed:
Microscopic description
Sections examined revealed malignant neoplasm composed of proliferating epitheloid and eosinophilic cytoplasm. The cells are arranged in cord and solid areas in myxoid with evident interstitial hemorrhage and hemosiderin laden macrophages.
Immunohistochemistry
Immunostaining using Bench Mark Ventana System revealed that the tumor cells showed:
-Positive reaction to CK (diffuse), Vimentin (diffuse), CD34 (few cells), and ERG (weak in few cells)
-INI-1: loss of nuclear expression
-Negative reaction to CK20, CK7, Glypican-3, C-KIT, PLAP, ALK, S100, Desmin, synaptophysin
-CD 99: inconclusive
-Ki-67 proliferation index is 40%
Diagnosis
Epithelioid sarcoma
Case Discussion
Intra-abdominal soft-tissue sarcomas are an uncommon yet important group of malignancies. The most common intra-abdominal sarcomas are GIST, liposarcoma, and leiomyosarcoma. GIST is the most common intraperitoneal sarcoma. Liposarcoma is the most common retroperitoneal sarcoma, and leiomyosarcoma is the second most common.
Epithelioid sarcomas represent one of a group called "Sarcomas of uncertain differentiation" which represent less than 1% of all soft tissue sarcomas, this group includes synovial sarcoma, epithelioid sarcoma, alveolar soft part sarcoma, extraskeletal Ewing sarcoma, desmoplastic small round cell tumor, and malignant perivascular epithelioid cell tumor (“PEComa”).
Epithelioid sarcomas have no characteristic imaging features.
This case is courtesy of Dr Fatma Ahmed, and Dr Lobna