case_images: PMC10477288_01
case_images: Gangrenous and ulcerated feet with radiological and histological findings. (A) Ulcerated and gangrenous feet. (B) CT aorta, showing periaortic sheathing (coated aorta). (C) Thoracic aorta with pericardial involvement. (D) CT-PET, demonstrating hairy kidneys. (E) FDG uptake in right distal femur. (F, G) CT-PET post MEK inhibition, demonstrating reduction in FDG uptake in distal femur and perinephric encasing. (H) Core biopsy from a peritoneal lesion, showing proliferation of histiocytic cells, with no significant atypia or mitosis. There is no significant inflammatory cell population within this infiltrate. (I, J) Histiocytic cells show strong and diffuse expression of CD14 and CD163, respectively. They do not show expression of S100, CD1a or Langerin. Images were taken from scanned slides at x20 magnification. FDG: Fluorodeoxyglucose; MEK: mitogen-activated protein kinase
case_images: rkad074f1.jpg
case_images: PMC10477288_01_rkad074f1.jpg
case_images: rkad074-F1
case_images: Dear Editor, A 62-year-old male presented with critical ischaemia of the lower limbs (Fig. 1A). Large vessel vasculitis (LVV) was diagnosed after CT angiogram demonstrated iliac, subclavian and carotid artery stenosis with aortitis (Fig. 1B). Repeat CT angiogram found that the thoracic aorta was involved, with infiltration of the pericardium (Fig. 1C). Brightly enhanced kidneys were suggestive of Erdheim-Chester disease (ECD), and increased uptake was confirmed on CT-PET (Fig. 1D). Sclerosis in the distal femora was in keeping with bone involvement (Fig. 1E). CT-guided biopsy from perinephric tissue demonstrated histiocytosis (Fig. 1H-J). In our patient, the MAP2K1 variant was identified, and he was started on an mitogen-activated protein kinase (MEK) inhibitor, trametinib, with good response (Fig. 1F, G).