The classic sonographic criteria of mesenchymal hamartoma were the cystic pattern that exhibited anechoic or predominant anechoic with variable thickness echogenic septa. Low-level echo fluid loculations may be noticed. Color Doppler imaging displays fairly tiny blood flow, which is restricted to septa .
At CT, MHL shows as a complex cystic mass. The cystic portion displays fluid density, while the stromal portion is hypodense to the adjacent hepatic parenchyma. Post-contrast studies, the septa, and solid portion enhancement were noted. Hemorrhage is not a frequent feature in mesenchymal hamartoma .
At MR imaging, the solid component may show low signal intensity to surrounding hepatic parenchyma on either T1 or T2WIs due to fibrosis. The cystic component is usually near fluid signal intensity on T2WIs. After dynamic sequences, mild enhancement is restricted to the septa and solid portions .
MHL is arranged of a mucous matrix and a large number of star and fusiform primary mesenchymal cells though the tumor cells themselves do not display heteromorphism .
UESL stakes several imaging and pathologic criteria with MHL, however, is picked in an elder age category (6 to 10 years old). At histopathologic assessment, UESL is recognized by the prevalent realization of hemorrhage and necrosis among malignant backgrounds .
A sole imaging distinctive criteria of UESL is a principally solid echo pattern in the US however cystic pattern at CT and MR imaging due to the high-water content of the abundant myxoid contents. CT shows chiefly fluid density (88% of tumor size) with soft tissue foci, generally at the margins and intervening different septal breadth. Central hyperdense foci signifying recent hemorrhage may also be existing. Calcifications are unusual [7, 8]. After contrast administration, mainly marginal enhancement is distinguished on delayed series. At MR imaging, UESL is mainly of fluid signal intensity on T1 and T2WI. Focal portions of high signal intensity T1 and relatively low signal intensity in T2WIs are often seen, which match with bleeding in the gross sectional anatomy. These hemorrhagic foci are superiorly realized with MR imaging than with CT [8, 9]. After dynamic sequences, heterogeneous enhancement of the peripheral and solid components of the lesion is detected. MR imaging added more information for the characterization of resectability and assessment of vascular pedicles, the biliary system, and locoregional lymph nodes .
Follow-up mesenchymal hamartoma is not favored due to the less incidence of progressive course, in addition to the scare recordings of malignant conversion to UESL. The long-term survival rate is great (90%), although inadequate resection was done .
The chief differential diagnostic issue is MHL, which is pathologically and radiologically analogous to UESL. The patient age category may support one diagnosis more than the other, as UESL is sporadic below the age of 5 years while MHL is mostly identified by the age of 2 years; though, histopathological correlation is essential to create a conclusive analysis [3, 7].
Of eleven patients spotted in analogous research, five cases of UESL (45%) evolved in the background of MHL with distinguishable transitional zones. Some proof recommends that pre-existing MHL may progress to malignant degeneration and advance into UESL. This variety of malignant conversion of hamartomatous entities is not a scarce outcome. It established a histologic association between UES and MH. The connection in immunohistochemical staining and clinical performances affords supplementary clues that MHL and UESL may be an evolving spectrum of the same disease, and reflect that some trigger or genetic predilection may be the core for the malignant transformation of benign MHL .
Also, another study stated that the pathologic evaluation of its case reveals MHL of the liver in association with several malignant sarcomatous elements, which advances the likelihood of it being a precursor lesion for UESL .
Our current case matched with the previously mentioned research studies.
However, still, the available radiological research studies that discuss the presence of UESL in the background of MHL scarcely. Complete resection stays the management backbone, but the involvement of multimodal treatment has shown a significant impact on the outcome, and this entity is currently assumed treatable. The utilization of neoadjuvant chemotherapy affords the majority of these neoplasms responsive to successful surgical excision [7, 8 ].
Our case was referred to a special pediatric cancer hospital to receive non-rhabdomyosarcoma protocol and follow-up by different imaging modalities showed no residual or recurrent tumors.