A 71-year-old male presented with a 3-month history of word-finding difficulties, confusion, and left leg weakness. CT head demonstrated several ill-defined hypodense areas within the right parietal and occipital subcortical white matter. MRI of the brain demonstrated a contrast-enhancing 3.2 cm lesion in the right occipital lobe, a 1.8 cm enhancing lesion in the right precentral gyrus, and multiple smaller enhancing lesions in the right periventricular region with associated vasogenic edema but no mass effect [Figure 1a]. PET/CT showed no evidence of systemic malignancy but visualized right posterior temporal, occipital and parietal lobe lesions [Figure 1b and c]. Susceptibility-weighted angiography (SWAN) imaging demonstrated a hemorrhagic component of the right occipital lobe lesion [Figure 1d].
A needle core biopsy was obtained of the right occipital lesion, and intraoperative frozen pathology was thought to be consistent with a lymphoma. Formal pathology, however, only showed an intense inflammatory process [Figure 2a and b] comprised foamy macrophages and T-cells with scattered small B-cells. These cells were CD3 [Figure 2c], CD163, Iba1, and CD68 positive. B cell immunohistochemistry was scantly positive [Figure 2d]. The T-cell population was found to be composed of more CD4+ than CD8+ cells.
Postoperatively, he was started on high-dose dexamethasone. However, this was discontinued once the formal pathology was available. A follow-up brain MRI after 1 month demonstrated a decrease in the size of all enhancing lesions. MRI of the total spine was without evidence of disease. Dexamethasone was subsequently tapered off given initial concern for sentinel lymphomatous lesions.
CSF studies, ordered 2 months after the patient's biopsy, were unremarkable for autoimmune, bacterial, viral, fungal, parasitic, or inflammatory etiologies. CSF flow cytometry was limited by the low cellularity of the specimen but revealed a predominance of CD5+ T cells. Repeat MRI brain off of corticosteroids demonstrated an interval increase in size and conspicuity of all previously observed enhancing lesions, and the decision was made to perform an excisional biopsy of the right occipital lesion.
The patient was brought to the operating room for excisional biopsy of the right occipital lesion. He was positioned supine with his head placed in the Mayfield head holder. The field was prepped and draped, and an incision was made down to the bone. A burr hole was made, and a craniotomy was turned over the lesion as confirmed with image-guidance. There was a pale tan pink discoloration of the brain. Several biopsies were obtained, and then the lesion was resected under the microscope and sent for pathology.
Further histological analysis demonstrated areas of macrophages/lymphocytes with markedly reactive astrocytes that showed quick transition to reactive less inflamed cortex. The lymphocytic population appeared small, but polymorphous, containing scattered plasma cells. There was marked perivascular inflammation but no fibrinoid necrosis. Flow cytometric and immunohistochemical workup failed to demonstrate a definitely clonal lymphocyte population. There was no evidence of demarcated myelin loss or a vasculitic process.
Two weeks postoperatively, he had worsening behavioral outbursts, frequent mood fluctuations, poor comprehension, and worsening balance. Given the clinical deterioration, he was restarted on high-dose dexamethasone. The following MRI demonstrated post-surgical changes with significant decrease in the size of the right occipital lesion [Figure 3]. His steroids were changed to a Prednisone taper starting at 60 mg that was tapered to 20 mg over the course of 6 weeks. Upon follow-up, he was noted to have improved cognitive processing and improved left-sided weakness. Given the clinical and radiographic responsiveness to steroids in the absence of infectious, inflammatory, or neoplastic etiologies, the diagnosis of SLIPPERS was made.