Calcifying pseudoneoplasm of the neuraxis (CAPNON) is a rare tumor-like lesion with unknown pathogenesis. It is likely under-reported due to diagnostic challenges including the nonspecific radiographic features, lack of diagnostic markers, and often asymptomatic nature of the lesions.

We performed detailed examination of 11 CAPNON specimens diagnosed by histopathology, with the help of electron microscopy and immunohistochemistry.

Electron microscopy revealed the presence of fibrillary materials consistent with neurofilaments. In addition to some entrapped axons at the periphery of CAPNONs, we discovered that all specimens stained positive for neurofilament-light (NF-L) within the granular amorphous cores, but not neurofilament-phosphorylated (NF-p). CAPNONs also showed variable infiltration of CD8+ T-cells and a decreased ratio of CD4/CD8+ T-cells, suggesting an immune-mediated process in the pathogenesis of CAPNON.

NF-L and CD4/CD8 immunostains may serve as diagnostic markers for CAPNON and shed light on its pathogenesis.

Lhermitte-Duclos disease (LDD) is a rare pathologic entity involving the cerebellum. The fundamental nature of the entity and its pathogenesis remain unknown, and considerable debate has centered on whether it represents a neoplastic, malformative or hamartomatous lesion. The cell or cells of origin remain incompletely defined. Previous reports of cases in the English literature have dealt predominantly with the clinical and pathological aspects yet few address issues of treatment.

A case of Lhermitte-Duclos disease (LDD) in a 54-year-old female leading to local compressive symptoms and obstructive hydrocephalus is presented. A craniectomy, in addition to a CI laminectomy followed by a decompressive duroplasty (using autologous fascia lata graft) was performed.

The patient clinically improved and follow-up MRI 11 months post-operatively revealed improvement in hydrocephalus.

The histological and immunohistochemical features of the lesion are described, emphasizing the role of an abnormal dysplastic granule cell layer. The evidence in favor of each of the major theories of pathogenesis, malformative and neoplastic is discussed. Based on these facts a form of surgical intervention involving decompressive duroplasty is proposed.

Statins have recently been reported to cause a rare autoimmune inflammatory and/or necrotic myopathy that begins or persists after drug cessation.

We report on 26 patients seen at a neuromuscular centre between 2005 and 2011 who demonstrated muscle weakness/myalgias and creatine kinase elevations during or after statin treatment with continuation of signs and symptoms despite statin withdrawal.

All patients were treated with immunosuppressive therapy with good response; all improved biochemically and 86% improved clinically. Sixty-five percent of patients who attempted to taper off immunosuppressive therapy relapsed. We report on a novel finding whereby five of the seven patients who underwent multiple biopsies throughout their disease demonstrated a transformation of their histological diagnosis, with four progressing from having myofibre necrosis with minimal or no inflammation to a diagnosis of polymyositis.

This study offers preliminary evidence that statin-associated necrotizing myopathy and statin-associated polymyositis may not be separate entities but are part of the same pathophysiological spectrum. Both entities respond well to immunosuppression.