Atypical Carotid Webs: An Elusive Etiology of Ischemic Stroke.

Objective: Typical carotid webs are nonatherosclerotic shelf-like projections of fibromyxoid tissue extending from the posterior wall of the proximal internal carotid artery. Carotid webs may precipitate acute embolic stroke, especially in younger patients. We describe our experience with pathology-proven carotid webs of atypical appearance, or atypical carotid webs (ACWs), a subset of carotid webs exhibiting abnormal location, morphology, or association with atherosclerotic changes.

Deep learning-based classifier for carcinoma of unknown primary using methylation quantitative trait loci.

Cancer of unknown primary (CUP) constitutes between 2% and 5% of human malignancies and is among the most common causes of cancer death in the United States. Brain metastases are often the first clinical presentation of CUP; despite extensive pathological and imaging studies, 20%-45% of CUP are never assigned a primary site. DNA methylation array profiling is a reliable method for tumor classification but tumor-type-specific classifier development requires many reference samples.

Atypical neurofibromas reveal distinct epigenetic features with proximity to benign peripheral nerve sheath tumor entities.

Background: Plexiform neurofibromas can transform into atypical neurofibromas (ANF) and then further progress to aggressive malignant peripheral nerve sheath tumors (MPNST). ANF have been described to harbor distinct histological features and frequent loss of CDKN2A/B. However, histological evaluation may be rater-dependent, and detailed knowledge about the molecular mechanisms of malignant transformation is scarce.

Diagnostic Pathology of Tumors of Peripheral Nerve.

Neoplasms of the peripheral nervous system represent a heterogenous group with a wide spectrum of morphological features and biological potential. They range from benign and curable by complete excision (schwannoma and soft tissue perineurioma) to benign but potentially aggressive at the local level (plexiform neurofibroma) to the highly malignant (malignant peripheral nerve sheath tumors [MPNST]). In this review, we discuss the diagnostic and pathologic features of common peripheral nerve sheath tumors, particularly those that may be encountered in the intracranial compartment or in the spine and paraspinal region.

Localized Hypertrophic Neuropathy as a Neoplastic Manifestation of KRAS-Mediated RASopathy.

Localized hypertrophic neuropathy is a rare Schwann cell proliferation that usually affects single nerves from the extremities, and it is of unclear etiology in its pure form. RASopathies are a defined group of genetic diseases with overlapping clinical features, usually secondary to germline mutations in genes encoding either components or regulators of the RAS/MAPK pathway. Herein, we report an 11-year-old boy presenting with café au lait spots and right leg length discrepancy.