Primary idiopathic CNS non-amyloidogenic light chain deposition disease complicated by treatment-resistant focal seizure disorder

Brain aggregoma with clonal B-cell perivascular proliferation detected by next-generation sequencing. A case report and review of the literature

“…The leading symptom of disease in the presented case was epileptic seizure, as it was in the additional 2 with similar locations [4,12]. Otherwise, there were hemiparesis with or without hemihypesthesia [10,11,15], headache with speech and visual disturbances [1,5], gait instability in the case with cerebellar location [17], and bulbar signs in the case with multifocal CLCV with severe medullary involvement [13]. The MRI presentation of all cases was very similar.…”

“…Another similarity between brain LCDD and PCNSL is the periventricular location in the majority of cases. In 7 cases, including the presented case, the lesion was located in the right occipital lobe close to the ventricle [1,4,5,11,12,18]. Even in the case with post-mortem brain examination, the largest lesion was in the same location [13].…”

“…In the presented case, NGS clonality testing showed monoclonal B-cell lymphocytes. In all other cases, monoclonal lymphoplasmacytic infiltrate was observed with κ-LC restriction in 4 cases [1,5,11,17], and λ-LC restriction in 2 cases [10,15], in contrast to amyloidomas of CNS, in which almost exclusively λ-LC have so far been described [8]. LC restriction in the lymphoplasmacytic infiltrate was not mentioned in the other 3 cases [4,12,13].…”

“…Specimens for microscopic observation of the lesions were obtained by stereotactic biopsy in 6 cases [4,[10][11][12]15,18], by craniotomy followed by excision of the lesion in 4 cases, including the presented one [1,5,17], and whole brain examination was performed in 1 case [13]. In stereotactic biopsy specimens, the exact location of the aggregates could not always be determined, while in the excised specimens after craniotomy, the location of aggregates was well defined: in 3 cases, including the presented one, the aggregates were parenchymal, sparing the vessel walls [5,17], and giving tumour-like LCDD called aggregoma, while in 1 case the aggregates were only in the vessel walls [1], giving focal CLCV. Multifocal CLCV with no parenchymal aggregates was clearly observed only in the case of whole brain examination [13].…”

“…Diffuse LCDD restricted to a single organ has also been described [16]. Only 10 cases of LCDD restricted to the brain have so far been described [1,4,5,[10][11][12][13]15,17,18]. The majority of them were aggregomas, with or without vascular involvement.…”