Erdheim-Chester disease (ECD) is a rare disorder characterized by excessive production and accumulation of histiocytes within multiple tissues and organs. ECD primarily affects adults, and symptoms vary depending upon the specific location and severity. Etiology is not always known, but some patients with ECD may have a non-inherited genetic change that allows histiocytes to reproduce uncontrollably. Currently, the cognitive outcomes of ECD are not well understood, and there are no previous neuropsychological findings in the literature. Thus, the objective of this case study was to describe the neuropsychological presentation and findings of an ECD case to inform diagnosis and treatment better.

The patient was a 64-year-old white, non-Hispanic, right-handed man diagnosed with ECD in 2017. ECD accounted for a constellation of medical problems, including diabetes insipidus, hypogonadism, and interstitial lung disease. A brain MRI in 2018 revealed orbital nodularities and pituitary infiltration thought to be consistent with ECD. The patient first noticed cognitive functioning difficulties in 2020 primarily related to short-term memory. Approximately two years later, he noted significant cognitive changes, including difficulties recalling recent events, dates, and conversations, problem-solving, and planning. He had difficulty driving and had two recent car accidents when leaving his driveway. Physically, he reported increased fatigue, unsteadiness, and occasional falls. In 2022, he had a brain MRI that demonstrated a progression of multiple diffuse cerebral, cerebellum, and brainstem lesions and cerebral volume loss compared to prior imaging. He was referred for a neuropsychological assessment to rule out a neurodegenerative disorder.

Neuropsychological data demonstrated moderate-to-severe deficits on tests of basic spatial working memory, visually based processing speed, visual memory, letter verbal fluency, and semantic verbal fluency. He demonstrated mild-to-moderate deficits on tests of basic auditory attention, verbal memory, higher-level visuospatial processing, abstract nonverbal reasoning, multistep, organization and planning, self-monitoring of performance quality, and fine hand and motor dexterity. He demonstrated variable initial learning of new information across modalities, although he did benefit from structured verbal material. Recognition was variable, with difficulty demonstrated in discriminating visual information presented, from similar competing information, along with availability recalling visual information. He showed average auditory-based divided attention, confrontational object naming, and abstract verbal reasoning. Regarding his emotional functioning, he reported mild depressive and anxiety symptoms.

To the best of our knowledge, this is the first report documenting detailed neuropsychological data on this rare disease. The case study documents widespread cognitive deficits with greater difficulty with visually based abilities than verbal abilities. Specifically, patients with ECD may present with cognitive difficulties in visual learning and memory, processing speed, visuospatial processing, select areas of executive/frontal systems, letter and semantic verbal fluency, and fine motor dexterity.