A Sheep in Wolf’s Clothing: An Atypical Etiology of a Cerebellar Lesion.
nitial History/Presentation: A 12-year-old, previously healthy female presented with acute, intractable headaches. Headaches were preceded by one month of lethargy, myalgias, upper respiratory symptoms, and 8-pound weight loss. Symptoms rapidly progressed over 48 hours with new onset confusion, irritability, and left gaze deviation prompting initial presentation. Physical Exam: Pertinent positives on exam included GCS 10-12, waxing/waning alertness, paucity of speech, left beat nystagmus, left gaze preference, dysmetria on finger-nose-finger testing, and episodic distress secondary to pain. Diagnostic Evaluation: Patient was initially seen at an outside facility where CT head revealed cerebellar edema with fourth ventricle effacement. MRI notable for T2 bright left cerebellar mass measuring 4x5x3 cm, crossing the midline, with mass effect on the fourth ventricle. She was given antibiotics, steroids, and antiepileptics and promptly transferred. On arrival to our facility, labs notable for normal CBC, CMP, and ESR. CRP elevated at 0.92 mg/dL. CSF with 7 nucleated cells, 70% neutrophils, normal cytology, and negative cultures. Blood cultures negative. CT venogram confirmed hypo-attenuating left cerebellar lesion with increasing hydrocephalus. MRI spine revealed multifocal leptomeningeal contrast enhancement. MRI spectroscopy showed FLAIR abnormality in the cerebellum favored to represent malignancy. Whole body PET and CT imaging with no additional sites of disease. The patient underwent mass resection with histopathologic diagnosis of angiosarcoma. Pathology slides reviewed and corroborated at two additional facilities. Whole transcriptome analysis subsequently revealed no pathogenic mutations. Based on the molecular findings, the patient was observed without intervention. Serial MRIs showed resolution of leptomeningeal findings and improved postoperative changes in her resection cavity. CSF remained negative for malignant cells. She has no evidence of disease over 6 months later. Diagnosis: Given the lack of pathogenic mutations, the patient was presumed to have resolving post-viral cerebellitis, which is supported by her continued clinical improvement without therapy. Discussion/Conclusion: This case represents a rare but clinically important diagnostic challenge faced by pediatricians, and highlights the importance of molecular data in cancer diagnosis. As cerebellitis and intracranial infection can mimic malignancy, comprehensive molecular analysis should be pursued to ensure accurate diagnosis and management. In this case, whole transcriptome sequencing conferred a fairly benign diagnosis, sparing the patient whole brain and spine radiation.