Isolated Perihepatic Peritoneal Leiomyoma: A Case Report

Abstract

Peritoneal leiomyomas are extremely rare. Most reported cases are that of disseminated peritoneal leiomyomatosis, making isolated leiomyoma an uncommon occurrence. Given that isolated leiomyoma is rare, the preoperative diagnosis of isolated leiomyoma is challenging. To date, very few reports have described the radiological findings of isolated peritoneal leiomyoma. This study aimed to present a rare case of isolated peritoneal leiomyoma in the perihepatic region of a 54-year-old female, and present the US, CT, and MRI based radiological findings of the case.

Keywords: Leiomyoma; Liver; Magnetic Resonance Imaging; Peritoneum; Tomography, X-Ray Computed.

Fig. 1. A 54-year-old female with peritoneal leiomyoma presented with a perihepatic mass.

A. Initial US (left) shows a well-defined hypoechoic mass of approximately 3.5 cm. After 7 years (right), this mass significantly increased to approximately 10 cm and changed to a heterogeneous hyperechoic form. B. Precontrast CT shows a well-defined smooth mass with low attenuation compared to the surrounding liver tissue. Postcontrast CT shows the large, lentiform-appearing perihepatic tumor has a slightly lower degree of contrast enhancement than the adjacent liver parenchyma. C. On MRI, the tumor shows heterogeneously high SI on T2WI and relatively homogenous low SI on pre-T1WI compared to the adjacent liver parenchyma, and early heterogenous and slow progressive enhancement without definite intratumoral necrosis. On DWI with a b-value of 800 s/mm², the mass shows a subtly high SI and a subtly high ADC value on the ADC map compared to liver parenchyma. The tumor exhibits several prominent intratumoral arterial vascular structures arising from the diaphragmatic side in arterial phase subtraction image (arrows) and a negative beak sign between the tumor and the liver on coronal T2WI indicating an extrahepatic mass. D. The gross surgical specimens appear as well-defined mass with a whitish cut surface (left). Microscopy shows proliferation of spindle cells with elongated nuclei and eosinophilic cytoplasm corresponding to smooth muscle fibers (middle, H&E stain, ×200). Immunohistochemical stain for desmin (right, ×200) is positive. ADC = apparent diffusion coefficient, DWI = diffusion-weighted imaging, H&E = hematoxylin & eosin stain, SI = signal intensity, WI = weighted image