Erdheim-Chester Disease Involving Lymph Nodes and Liver Clinically Mimicking Lymphoma: A Case Report

Pathologic characteristics of histiocytic and dendritic cell neoplasms

Histiocytic and dendritic cell neoplasms comprise diverse tumors originating from the mononuclear phagocytic system, which includes monocytes, macrophages, and dendritic cells. The 5th edition of the World Health Organization (WHO) classification updating the categorization of these tumors, reflecting a deeper understanding of their pathogenesis.In this updated classification system, tumors are categorized as Langerhans cell and other dendritic cell neoplasms, histiocyte/macrophage neoplasms, and plasmacytoid dendritic cell neoplasms. Follicular dendritic cell neoplasms are classified as mesenchymal dendritic cell neoplasms within the stroma-derived neoplasms of lymphoid tissues.Each subtype of histiocytic and dendritic cell neoplasms exhibits distinct morphological characteristics. They also show a characteristic immunophenotypic profile marked by various markers such as CD1a, CD207/langerin, S100, CD68, CD163, CD4, CD123, CD21, CD23, CD35, and ALK, and hematolymphoid markers such as CD45 and CD43. In situ hybridization for EBV-encoded small RNA (EBER) identifies a particular subtype. Immunoprofiling plays a critical role in determining the cell of origin and identifying the specific subtype of tumors. There are frequent genomic alterations in these neoplasms, especially in the mitogen-activated protein kinase pathway, including BRAF (notably BRAF V600E), MAP2K1, KRAS, and NRAS mutations, and ALK gene translocation.This review aims to offer a comprehensive and updated overview of histiocytic and dendritic cell neoplasms, focusing on their ontogeny, morphological aspects, immunophenotypic profiles, and molecular genetics. This comprehensive approach is essential for accurately differentiating and classifying neoplasms according to the updated WHO classification.

Erdheim–Chester Disease with Isolated CNS Involvement: A Systematic Review of the Literature

Erdheim–Chester disease (ECD) is a rare, sporadic, non-Langerhans cell histiocytosis that can have various presentations and higher mortality in patients presenting with neurological symptoms. We performed a systematic review to investigate and chronicle the frequency of neurological manifestations, imaging findings, treatments, and outcomes in published ECD patients presenting with neurological symptoms. A PubMed literature search was conducted for articles (published between January 1980 and June 2021) on ECD cases presenting with neurological manifestations. We analyzed the data of 40 patients, including our patient. Cranial neuropathies and ataxia were the most frequent clinical manifestations. A total of 50% of the symptomatic ECD CNS lesions were intraparenchymal and nearly 33% of patients died due to the disease itself or complications. CNS involvement may be the only manifestation of ECD and sometimes may require a repeat biopsy with IHC testing for excellent treatment outcomes.

Erdheim-Chester disease with long-standing diabetes insipidus and generalized edema

Erdheim-Chester disease (ECD) is a rare non-Langerhans histiocytosis. ECD is detected more frequently due to increased awareness of healthcare providers and improved diagnostic tools. This report describes a 51-year-old woman with a history of weakness, bone pain, xanthelasma palpebrarum, and diabetes insipidus. ECD is a multisystemic condition with a poor prognosis. This disease should be considered in patients with diabetes insipidus, bone pain, and multiorgan involvements.

New causes of hypophysitis

Hypophysitis is a rare entity characterized by inflammation of the pituitary gland and its stalk that can cause hypopituitarism and/or mass effect. Etiology can be categorized as primary or secondary to systemic disease, but may also be classified according to anatomical and hispathological criteria. Newly recognized causes of hypophysits have been described, mainly secondary to immunomodulatory medications and IgG4-related disease. Diagnosis is based on clinical, laboratory and imaging data, whereas pituitary biopsy, though rarely indicated, may provide a definitive histological diagnosis. For the clinician, obtaining a broad clinical and drug history, and performing a thorough physical examination is essential. Management of hypophysitis includes hormone replacement therapy if hypopituitarism is present and control of the consequences of the inflammatory pituitary mass (e.g. compression of the optic chiasm) using high-dose glucocorticoids, whereas pituitary surgery is reserved for those unresponsive to medical therapy and/or have progressive disease. However, there remains an unmet need for controlled studies to inform clinical practice.

Primary Necrobiotic Xanthogranulomatous Sialadenitis with Submandibular Gland Localization without Skin Involvement

Necrobiotic xanthogranulomatous reaction is a multiorgan, non-Langerhans cell histiocytosis with an unknown etiology. Occurrence in the salivary gland is extremely rare. We recently identified a case of necrobiotic xanthogranulomatous sialadenitis in a 73-year-old Korean woman who presented with a painless palpable lesion in the chin. There was no accompanying cutaneous lesion. Partial resection and subsequent wide excision with neck dissection were performed. Pathological examination showed a severe inflammatory lesion that included foamy macrophages centrally admixed with neutrophils, eosinophils, lymphocytes, plasma cells, and scattered giant cells, as well as necrobiosis. During the 12-month postoperative period, no grossly remarkable change in size was noted. Necrobiotic xanthogranulomatous inflammation may be preceded by or combined with hematologic malignancy. Although rare, clinicians and radiologists should be aware that an adhesive necrobiotic xanthogranuloma in the salivary gland may present with a mass-like lesion. Further evaluation for hematologic disease and close follow-up are needed when a pathologic diagnosis is made.