Peritoneal disease in the pediatric population is exceedingly rare. When encountered, differential diagnoses typically include infection, inflammation, and metastatic disease. However, we report a case of malignant epithelial peritoneal mesothelioma to emphasize that this primary malignancy should also be considered. A 14 year old male with a history of growth hormone deficiency, gastroesophageal reflux disease, and asthma presented to his primary care physician with chronic abdominal pain, mild anemia, and over 20 pound weight loss in a 9 month period. Outpatient workup by gastroenterology showed elevated ESR and CRP and a single hyperplastic polyp on endoscopy. MRI enterography of the abdomen and pelvis with intravenous contrast was completed to evaluate for inflammatory bowel disease. This exam revealed a thickened omentum, hyperenhancement of the peritoneum and omentum, peritoneal nodularity, a moderate to large volume of ascites, and enhancing nodules along the superior surface of the diaphragm. The nodules were further evaluated with a dedicated CT chest, abdomen, and pelvis, which confirmed the above findings. Differential diagnosis of an abdominal mesothelial process as above includes familial mediterreanean fever, malignancy, and infection. Laparoscopic omental and peritoneal biopsies showed mesothelial hyperplasia. Genetic testing returned positive for a CDKN2A homozygous and heterozygous deletion, confirming the diagnosis of diffuse malignant peritoneal mesothelioma. The patient is currently under treatment with a cisplatin-based chemotherapy regimen and is being closely followed. Our case exemplifies the symptoms, imaging findings, diagnosis, and treatment associated with malignant epithelial peritoneal mesothelioma. Read More

Meeting name: SPR 2020 Annual Meeting & Postgraduate Course , 2020

Authors: Lee Samantha, Bellew Elizabeth, Amodio John

Keywords: Mesothelioma, Peritoneal Mesothelioma

<b>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.</b> <b>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.</b> <b>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.</b> Read More

Meeting name: SPR 2020 Annual Meeting & Postgraduate Course , 2020

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

Keywords: Rhabdomyosarcoma, Sclerosing Spindle Cell Rhabdomyosarcoma, Vascular Malformation