Contributed by Pasquale Strianoa, Alessandro Consalesb , Mariasavina Severinoc, Giulia Pratod, Corrado Occellae, Andrea Rossic, Armando Camab, Paolo Nozzaf , Maria Giuseppina Bagliettod
aPediatric Neurology and Neuromuscular Diseases Unit; bNeurosurgery Unit; cNeuroradiology Unit; dChild Neuropsychiatry Unit; eDermatology Unit; fNeuropathology Unit; Gaslini Children's Hospital, Italy.
CLINICAL HISTORY AND IMAGING STUDIES
A 3-year-old boy was referred for pre-surgical evaluation due to drug-resistant complex partial seizures. The patient was born to unrelated healthy parents and had developed normally. There was no family history of any central nervous system (CNS) disease. His seizures started at the age of 4 months and were characterized by daily, brief (30-60 seconds) episodes of staring, gestural automatisms, and tachycardia, followed by somnolence or headache. From age 14 months the boy started suffering also from frequent left focal motor seizures often resulting in secondarily generalization. At our observation, seizures still occurred daily despite treatment with several antiepileptic drugs. In addition, his parents had also noted initial worsening of cognitive function. Dermatologic evaluation revealed a large congenital nevus on the scalp (Fig 1) and two small black pigmented nevi on gluteus and abdomen. Electroencephalographic recordings showed frequent slow and sharp waves over the right temporal region (Figs 2 and 3). Brain MRI showed a focal lesion in the right uncus. The lesion was hyperintense on T1-weighted (Figs 4 and 5) and hypointense on T2-weighted images (Fig 6) with no gadolinium enhancement. No mass effect or surrounding edema was evident. A right anterior temporal lobectomy and hippocampectomy was performed (Figs 7, 8 and 9). Intraoperative electrocorticography before resection revealed active spikes around the lesion. The postoperative course was uneventful. After surgery, the boy remained seizure-free at the 15-months follow-up.
GROSS AND MICROSCOPIC PATHOLOGY
On gross inspection, the uncus was replaced by a grayish-to-black friable soft tissue without definite mass formation (Fig 9). The microscopic examination of the resected tissue revealed the presence in the leptomeninges of nests of melanin-containing cells with round or oval nuclei and eosinophilic cytoplasm (Figs 10, 11, 12 and 13) heavily infiltrating the perivascular and Virchow-Robin spaces. These cells and their nuclei were uniform in shape and size, showing no cellular or nuclear atypia. Mitoses were absent. The proliferative index was low. No Ki67-labeled nuclei were present. The cells were immunostained with antibodies against S100 protein (not shown) and HMB45 (Fig 14) but were unreactive for MAP2, GFAP, and epithelial membrane antigen (not shown). The temporal cortex was normal, as confirmed by the Neu-n immunohistochemical staining (Fig 15). No dysmorphic neurons were observed.