Imaging in Erdheim-Chester Disease.

Erdheim-Chester disease (ECD) is a rare, multisystemic, inflammatory, non-Langerhans cell histiocytic neoplasm. The discovery of recurrent and somatic mutations in the mitogen-activated protein kinase signaling pathway, most commonly BRAFV600E, has led to a reclassification of ECD from an inflammatory disorder to a neoplastic process. It is now included in the revised 2016 World Health Organization classification of hematopoietic tumors and in the Langerhans group in the revised 2016 Histiocytosis Classification of the Histiocyte Society. When symptomatic, ECD most commonly manifests with bone pain and fatigue. Also, neurologic manifestations, central diabetes insipidus, exophthalmos, and periorbital xanthelasma-like lesions are frequently encountered. Pathologic findings may vary depending on the site of biopsy and may display a spectrum of features. Thus, due to the diverse clinical presentation and variable histologic findings, imaging can often show the first sign of the disease. Radiologic findings are, however, interpreted in conjunction with clinical and histologic findings to establish the diagnosis of ECD. From providing classic findings that facilitate diagnosis to helping radiologists determine the extent of disease and predicting a prognosis, the role of radiology in ECD has evolved with the understanding of the disease itself. Insights into the molecular pathogenesis and the development of targeted therapeutic agents along with approval of vemurafenib and cobimetinib have necessitated revision of the guidelines for the management of ECD. The authors discuss various radiologic findings of ECD and differential diagnoses by using an organ system-based approach and briefly describe the revised consensus recommendations for evaluation, diagnosis, and treatment based on the International Medical Symposia on ECD from a radiologist's perspective. ©RSNA, 2024 Supplemental material is available for this article. The full digital presentation is available online.

Atypical Bilateral Posterior Semicircular Canalolithiasis - A Case Series.

ABSTRACT: Barany Society includes bilateral typical posterior semicircular canal benign paroxysmal positional vertigo (PSC-BPPV) in its classification of multicanal subtype. In the past decade, less-common and atypical subtypes of PSC-BPPV, like short-arm and non-ampullary arm posterior semicircular canalolithiasis, have emerged, requiring the conduct of conventional and auxiliary positional tests on both sides to uncover their bilaterality. Authors hereby report three atypical less-common subtypes of bilateral PSC-BPPV, discussing their clinicodemographic profiles, management by repositioning maneuvers and physical therapy, and follow up. Both Case 2 and Case 3 are precisely tri-canalolithiasis (bilateral ampullary arm posterior semicircular canalolithiasis with co-occurring right non-ampullary arm posterior semicircular canalolithiasis in Case 2 and bilateral short arm with co-occurring left ampullary arm posterior semicircular canalolithiasis in Case 3), which has not been reported previously in the literature. There has been only one previously reported case of bilateral non-ampullary arm semicircular canalolithiasis, and it is now observed in Case 1.

Association of Dengue with Longitudinally Extensive Transverse Myelitis and Subarachnoid Hemorrhage: An Unusual Presentation.

Association of dengue fever with transverse myelitis is a rare phenomenon; involvement of a long segment is even rarer. We describe a middle-aged female who presented with weakness of bilateral lower limbs and urinary retention 4 days after recovery from dengue fever. She, in addition, had a sensory level up to the level of nipples. Magnetic resonance imaging confirmed the diagnosis of longitudinally extensive transverse myelitis. Besides, the patient had spontaneous subarachnoid hemorrhage (SAH) in the absence of dengue hemorrhagic fever. The patient was started on steroids along with rehabilitation. Our case highlights the extensive involvement of spinal cord in the postinfectious phase of dengue and inclusion of this arboviral disease in the differential diagnoses of myelitis as well as an etiology of SAH.