Erdheim-Chester Disease: A Rare Non-Langerhans Cell Histiocytosis with Pathognomonic Multisystem Imaging Findings: Case Report Illustrating the Classic Radiological Triad

Sachin Jain

Abstract: Background: Erdheim?Chester disease (ECD) is a rare non-Langerhans cell histiocytic neoplasm characterised by xanthogranulomatous infiltration of multiple organ systems by foamy CD68-positive, CD1a-negative histiocytes. The condition produces a highly characteristic constellation of skeletal, retroperitoneal and cardiovascular imaging findings, and in the majority of cases the radiologist is the first physician to raise the diagnosis. Case Presentation: We report a case of ECD in a middle-aged male who presented with insidious bilateral knee pain, polyuria and incidentally detected renal impairment. Plain radiographs of both lower limbs demonstrated bilateral, symmetric metadiaphyseal osteosclerosis of the distal femora and proximal tibiae with characteristic sparing of the epiphyses. Contrast-enhanced computed tomography (CECT) of the abdomen revealed symmetric perinephric soft-tissue infiltration producing the ?hairy kidney? appearance with thickened bridging perirenal septa, bilateral hydroureteronephrosis, and circumferential periaortic soft tissue extending from the descending thoracic aorta to the iliac bifurcation, constituting the ?coated aorta? sign. CT of the thorax showed smooth interlobular septal thickening, pericardial thickening and a right atrial pseudotumour. Magnetic resonance imaging of the sella demonstrated loss of the posterior pituitary bright spot with infundibular thickening. Technetium-99m methylene diphosphonate (99mTc-MDP) bone scintigraphy showed intense symmetric tracer uptake in the distal femora and proximal tibiae. Management and Outcome: Image-guided biopsy of the perinephric soft tissue demonstrated foamy histiocytes within a fibrotic stroma that were immunoreactive for CD68 and negative for CD1a and S100, confirming the diagnosis. Molecular analysis identified a BRAF V600E mutation, and targeted therapy with a BRAF inhibitor was initiated. Interval imaging at six months showed regression of the periaortic and perinephric soft tissue with improvement in hydronephrosis. Conclusion: This case underscores the pivotal role of imaging in the recognition of ECD. The triad of bilateral symmetric metadiaphyseal osteosclerosis of the long bones, hairy kidneys and coated aorta is sufficiently distinctive to permit a confident radiological suggestion of the diagnosis, allowing targeted biopsy, molecular characterisation and early institution of MAPK-directed therapy.

Keywords: Erdheim-Chester Disease, Histiocytosis Non-Langerhans-Cell, Tomography X-Ray Computed, Osteosclerosis, Retroperitoneal Fibrosis, Proto-Oncogene Proteins B-raf.

How to Cite?: Sachin Jain, "Erdheim-Chester Disease: A Rare Non-Langerhans Cell Histiocytosis with Pathognomonic Multisystem Imaging Findings: Case Report Illustrating the Classic Radiological Triad", Volume 15 Issue 8, August 2026, International Journal of Science and Research (IJSR), Pages: 178-181, https://www.ijsr.net/getabstract.php?paperid=MR26804021748, DOI: https://dx.doi.org/10.21275/MR26804021748

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