UCLA Radiological Sciences Proceedings

Histiocytoses are rare disorders characterized by abnormal proliferation of histiocytic cells in tissues and organs. They have a broad clinical spectrum and are traditionally categorized as Langerhans cell histiocytosis (LCH) and non-Langerhans cell histiocytosis (N-LCH), but recent evidence highlights a molecular and clinical overlap between LCH and a type of N-LCH known as Erdheim-Chester disease (ECD). While both disorders have distinct features, up to 20% of ECD patients may present with concurrent LCH lesions. Overlap between LCH and ECD is increasingly recognized, but reports of imaging of this phenomenon are scarce. Here, we present a rare case of directly contiguous LCH and ECD lesions in a 69-year-old woman and discuss the radiologic and histopathologic findings as well as the classification of these findings within the revised histiocytosis system.

Leber hereditary optic neuropathy (LHON) is a rare disorder that results in loss of central vision. Although the initial onset of LHON is most commonly seen in patients aged 15-35 years, it may occur at any age. The disorder is more common in men than women and is known to be caused by one of three mitochondrial DNA point mutations: 11778G>A, 3460G>A, or 14484T>C. Whereas the diagnosis of LHON is conventionally based on a patient’s clinical presentation, family history, and the results of ophthalmologic examination and genetic testing, it can significantly benefit from early contribution of neuroimaging. We report a case of LHON in a 36-year-old woman with low visual acuity and progressive worsening of vision for 7 months, a family history of LHON, and abnormal central hyperintense signal within the optic nerves on T2-weighted fat-saturated magnetic resonance imaging of the orbits. Some etiopathogenetic and neuroimaging aspects of LHON as well as challenges in diagnosis and treatment of patients with the disorder are also discussed.

Stump appendicitis is an inflammation of appendiceal remnant after incomplete appendectomy. However, the inclusion of appendectomy in a patient’s medical history often obfuscates a diagnosis of appendicitis, causing a delay in diagnosis and potentially leading to increased morbidity. Awareness of stump appendicitis can help radiologists distinguish this rare condition from more common entities. We report two cases of stump appendicitis that were correctly identified at the patients’ time of presentation to the emergency department. In one case, the patient presented with recurrent stump appendicitis. In this case series, we discuss the radiographic features, clinical considerations, and treatment of stump appendicitis.