Bellew Elizabeth,  Sonstegard Anna Marie,  Finelt Nika,  Goldfisher Rachelle

Final Pr. ID: Poster #: CR-004

A full-term male was born with a 7 x 7 cm subcutaneous mass with central dark blue discoloration and peripheral erythema on the right flank/buttock. Initial hip and pelvis radiograph at one day old did not show evidence of calcifications. An ultrasound demonstrated an ill-defined, heterogeneous mass with internal vascularity with invasion of underlying muscle. MRI of the abdomen and pelvis with contrast at two days of age showed a T2 hyperintense mass with mild postcontrast enhancement within the right flank with infiltration of the underlying muscles including the right psoas, iliacus, gluteal, and the left erector spinae. The differential diagnosis included: kaposiform hemangioendothelioma, rhabdomyosarcoma (RMS), tufted angioma and neuroblastoma.

Given the broad list of differential diagnoses, a core biopsy of the right buttocks was obtained at 6 days of age to further characterize the lesion. Hematoxylin and eosin stained sections demonstrated highly collagenized and sclerotic spindle cells involving the adipose tissues extending into the dermis. Immunohistochemical stained sections showed positivity to desmin, myogenin and MyoD1. Fluorescence in situ hybridization studies indicated the presence of a VGLL2 gene rearrangement. These pathologic findings were consistent with sclerosing spindle cell RMS. At 13 days old, a PET scan showed the right flank lesion with minimal to no FDG uptake, a finding which is consistent with sclerosing RMS given that this sub-type consists mainly of collagen. There were no pulmonary nodules. After multiple chemotherapy cycles, subsequent MRIs of the abdomen and pelvis showed no residual enhancing lesion. The patient will be closely followed for local recurrence.

RMS, the most common soft tissue tumor seen in children, are mesenchymal tumors of skeletal muscle and are most often seen in head and neck, but are less commonly noted on the flank. Sclerosing spindle cell RMS is a subtype often seen in childhood, but exceedingly rare in newborns. Cutaneous RMS should be considered in the differential diagnosis of a large subcutaneous lesion in a newborn. Read More

Authors:  Bellew Elizabeth , Sonstegard Anna Marie , Finelt Nika , Goldfisher Rachelle

Keywords:  Rhabdomyosarcoma, Sclerosing Spindle Cell Rhabdomyosarcoma, Vascular Malformation

Jin Annie,  Bao Shashan

Final Pr. ID: Poster #: CR-015

Rhabdomyosarcoma is a common pediatric soft tissue cancer with about 31% of cases in the urinary tract and 25% of cases in the head and neck. Although rhabdomyosarcomas are common, primary intrahepatic rhabdomyosarcomas are very rare and have a poor prognosis. In fact, there have only been 20 reported cases from 1956 through 2017, and the mean survival time of 9.25 months.

A 3-year-old male with a history of constipation presented with a 3-days of low-grade fevers of 99-100 F, periumbilical pain, and anorexia. On physical exam, there was a palpable, tender RUQ mass. Labs showed an elevated ALT of 159, AST of 179, and alkaline phosphatase of 748. A radiograph of the abdomen showed a soft tissue opacity in the right upper quadrant which displaced the large and small bowel loops. Further imaging included an ultrasound, CT, and MRI. The ultrasound confirmed a large mostly solid mass in the right hepatic lobe. CT imaging showed a large heterogeneous liver mass measuring 10.5 x 10.0 x 14.0 cm. The mass extended superiorly to the dome of the liver, involved the caudate lobe, and compressed the IVC. An indeterminate lucency of the right femoral neck was also noted. A follow up MRI showed that the liver mass displaced the hepatic veins, main portal vein and right portal vein. Additionally, innumerable lesions were found on the axial skeleton and periportal lymphadenopathy was seen suggesting metastasis. PET scan further confirmed bony metastasis of the right femur. Initially, hepatoblastoma was highest on the differential. However, liver wedge biopsy showed myxoid spindle cell areas and small round blue cell areas. These findings favored the diagnosis of rhabdomyosarcoma as opposed to hepatoblastoma which would have had an epithelial component. Bone marrow biopsy further confirmed metastasis. As a result of this diagnosis, the patient was started on vincristine, dactinomycin, cyclophosphamide. Pain was controlled with morphine and acetaminophen. Nausea was controlled with Ativan, Zofran, Reglan, and Benadryl. The patient’s abdominal distension and constipation responded well to a stool regimen and multiple enemas. The patient was discharged in stable condition with oncology follow up.

Hepatic rhabdomyosarcoma is a rare malignancy, and early diagnosis and treatment has been beneficial in prolongation of mean survival time. Diagnostic imaging modalities and pathology findings are an essential part of the work up and can be used to guide the treatment and management. Read More

Authors:  Jin Annie , Bao Shashan

Keywords:  Hepatic Rhabdomyosarcoma, Spindle Cell, Diagnostic Imaging

Almehdar Abeer,  Alshehri Ebtehaj

Final Pr. ID: Poster #: EDU-072

Rhabdomyosarcomas are heterogeneous group of malignancies of mesenchymal cell origin. It is the commonest pediatric soft-tissue sarcoma, representing 3 – 5 % of all malignancies in childhood.

Imaging provides crucial information early in the diagnosis by defining the exact location of the lesion and offering a differential diagnosis, thereby guiding the subsequent steps of the diagnostic analysis and follow up.

Although these tumors can arise almost anywhere, the most common locations for these tumors to develop are in the structures of the head and neck, the genitourinary tract, and the extremities. Unusual locations are not an infrequent occurance as well the rare and the uncommon behavior of the usual RMS.

In this review, we address the characteristic imaging features, discuss the most appropriate imaging techniques and offer an overview of differential diagnostic consideration of some of the unusual RMS. Read More

Authors:  Almehdar Abeer , Alshehri Ebtehaj

Keywords:  Rhabdomyosarcoma, Unusual

Nunes João,  Pinto Daniela,  Melão Lina,  Bom Sucesso Maria

Final Pr. ID: Poster #: EDU-080

Paediatric soft-tissue sarcomas encompass a diverse group of malignant mesenchymal tumours with overlapping imaging features. Although differing in molecular background, these tumours often appear radiologically similar, posing diagnostic challenges even to experienced radiologists. Rhabdomyosarcoma, the most frequent subtype, illustrates the broad radiologic spectrum of these lesions.
Radiologic evaluation is pivotal—not only for staging and therapy planning, but also for distinguishing viable tumour from post-treatment fibrosis or benign mimics. MRI remains the cornerstone of assessment, providing superior soft-tissue contrast and functional information through diffusion-weighted and contrast-enhanced sequences, which improve the detection of subtle tumour viability and therapy response.

Rhabdomyosarcomas usually manifest as heterogeneous soft-tissue masses that are isointense to muscle on T1 and hyperintense on T2-weighted imaging, reflecting variable amounts of necrosis, haemorrhage, and myxoid stroma. Embryonal rhabdomyosarcoma, the most frequent subtype, predominates in younger children and typically arises in the head and neck, genitourinary tract, or biliary system. It appears as an ill-defined, infiltrative mass with heterogeneous enhancement and restricted diffusion in solid components. The botryoid subtype, a variant of the embryonal form, develops in mucosa-lined cavities such as the biliary tree, bladder, or vagina, presenting as a grape-like polypoid intraluminal mass often causing luminal or ductal dilatation. Alveolar rhabdomyosarcoma, more frequent in adolescents and in the extremities or trunk, tends to be better defined, sometimes producing osseous erosion or fascial invasion, and often demonstrates more pronounced diffusion restriction due to its higher cellularity. These anatomic and morphologic distinctions provide essential clues for biopsy targeting, staging, and multidisciplinary planning.

By integrating current literature and representative institutional cases, this poster offers a focused visual guide to the MRI hallmarks and interpretative challenges of paediatric rhabdomyosarcoma, highlighting the radiologist’s role in tumour characterisation and multidisciplinary care. Read More

Authors:  Nunes João , Pinto Daniela , Melão Lina , Bom Sucesso Maria

Keywords:  Rhabdomyosarcoma, Oncology