Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids, a mimicker of malignancy: a case report and review of the literature.

Background: Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids is a clinically and radiographically distinct inflammatory syndrome affecting multiple structures of the brain, including the cerebellum, brainstem, and spinal cord. The clinical presentation can be variable, including ataxia, nystagmus, dysarthria, dysphagia, and other subacute brainstem, cranial nerve, or cerebellar symptoms. These symptoms can be subacute to chronic, episodic, and progressive, making the diagnosis challenging. The hallmark radiographic magnetic resonance imaging findings are gadolinium-enhancing punctate lesions predominantly "peppering" the pons in a perivascular pattern.
Case Presentation: Here, we describe a case and literature review of a 74-year-old Caucasian male who presented with subacute symptoms of ataxia, diplopia, and generalized fatigue. Physical examination was notable for horizontal nystagmus and wide-based gait. Magnetic resonance imaging revealed angiocentric enhancement predominantly in the brainstem and cerebellum, with involvement of the basal ganglia, thalami, and supratentorial white matter. Meanwhile, a screening computed tomography scan demonstrated a right upper lobe mass with biopsy proving primary lung cancer. Biopsy of one of the brain lesions showed perivascular infiltrate primarily composed of CD3+ T cells, scattered CD20+ B cells, and no signs of malignancy. The patient was started on high-dose glucocorticoids followed by a maintenance regimen with rapid improvement clinically and radiographically. Given extensive work-up was negative, these clinical and radiographic findings were consistent with chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids.
Conclusions: This case illustrates the difficulty of diagnosing chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids, given its variable presentation, lack of specific laboratory findings, and poorly understood pathogenesis. We demonstrate a case that responded well to oral corticosteroid burst followed by a taper to the lowest corticosteroid dose clinically possible. Failure to recognize this syndrome could result in permanent central nervous system morbidity. Therefore, earlier recognition is crucial for this treatable condition.