DON'T “MIS-C” THE CANCER: A CASE REPORT OF INCIDENTALLY DIAGNOSED WILMS TUMOR DURING ACUTE MIS-C

ABSTRACT

Background: Incidental diagnosis of malignancy during unrelated illness is challenging, both for diagnostic clarity and therapeutic decision-making. There are reported cases of incidental discovery of Wilms tumor (WT) in the setting of trauma, but there are none reported in the setting of acute inflammatory illness, such as Multisystem Inflammatory Syndrome in Children (MIS-C), and thus no guidance regarding timing of definitive therapy. Objectives: We describe a patient with MIS-C and incidentally diagnosed WT in order to inform the management of future patients with simultaneously diagnosed malignancy and acute inflammatory illness. Design/Method: Information was obtained by retrospective review of the electronic health record. Results: A healthy 5-year-old female presented with six days of fever, cervical lymphadenopathy, urinary symptoms, and rash. Labs showed acute kidney injury, prompting imaging that revealed a left-sided renal mass, most likely a WT. The constellation of signs and symptoms was initially suggestive of obstructive uropathy resulting in urinary tract infection. However, subsequent development of conjunctivitis and oral mucosal changes, positive SARS-CoV-2 nucleocapsid antibodies, rising inflammatory markers, and mild-moderate coronary artery dilation on echocardiogram, made MIS-C the most fitting diagnosis. The patient rapidly improved after initiation of aspirin, methylprednisolone, and intravenous immunoglobulin. Cross-sectional imaging showed no metastatic disease or local tumor invasion. A multidisciplinary team of pediatric subspecialists discussed appropriate timing for upfront resection and decided to defer surgery for at least two weeks while inflammation resolved. Unfortunately, the patient continued to have ongoing inflammation requiring a prolonged steroid course, and surgery was ultimately deferred until one month following diagnosis. Surgery was uncomplicated and pathology demonstrated stage II favorable histology WT. Chemotherapy began on post-operative day 9. Conclusion: The lack of published cases of malignancy incidentally discovered during acute illness, coupled with the rapidly rising rate of pediatric cases of COVID-19 and MIS-C, present a challenge for clinicians who must treat the concurrent conditions. This report highlights the complexities of managing a WT for which upfront resection is standard in the United States. Surgery is typically performed quickly due to the fast-growing nature and risk of rupture. Reports of paraneoplastic inflammatory syndromes (non-WT) suggest that tumor resection in the setting of acute inflammation is safe, but pediatric data remains scarce. This patient's multidisciplinary team chose to delay tumor resection given the potential morbidity of major surgery in the setting of a raging inflammatory state. The patient had a favorable clinical outcome both in terms of her MIS-C and WT.