CPD • Clinicopathological case Papulonodular lesions, gynaecomastia and retroperitoneal fibrosis V. Di Lernia and C. Ricci Department of Dermatology, Arcispedale S. Maria Nuova, Reggio Emilia, Italy doi:10.1111/j.1365-2230.2009.03643.x Clinical findings A 47-year-old man presented with persistent chest pain and fatigue. He had been well until 1 year earlier, when gynaecomastia developed. He had been evaluated at another facility, where a diagnosis of prolactin-releasing pituitary microadenoma was made, based on raised levels of prolactin and magnetic resonance imaging of the brain. At his presentation to us, he was found to have multiple, asymptomatic, yellowish to skin- coloured, well-defined papulonodular lesions, 3–5 mm in diameter, localized to the trunk, buttocks and limbs (Fig. 1a). These had been present for about 10 years. Chest radiography showed pronounced enlargement of the cardiac profile, and echocardiography showed evidence of a marked pericardial effusion. Computed tomography of the chest, abdomen and pelvis revealed a homogeneous mass of soft-tissue density coating the thoracic and abdominal aorta and surrounding both kidneys. Osteosclerotic lesions involving the tibias and increased bilateral tracer uptake by the long bones on 99m Tc-methylene diphosphonate bone scintigraphy were also found. Histopathological findings On histopathological examination of two papulonodular skin lesions, a normal epidermis and a dermal infiltrate of monomorphous spindle-shaped histiocytes without mitotic activity was aeen (Figs 1b,c). On immuno- histochemistry, histiocytes had clear staining for CD68 (Fig. 2), whereas staining for CD1a and S-100 was negative. Electron microscopy studies disclosed no Birbeck granules in the histiocytes. Computed tomography-guided biopsy of the perinephric soft tissue showed a diffusely fibrotic tissue with a population of infiltrating histiocytes, which stained positive for CD68 and negative for S100 and CD1a, analogous to skin lesions. What is your diagnosis? Diagnosis Erdheim–Chester disease (ECD). Discussion ECD is a rare multisystemic, progressive, non- Langerhans cell histiocytosis (non-LCH) characterized by the xanthomatous infiltration of tissues with foamy histiocytes. The age of presentation is usually 40–60 years. The most common clinical sign is bone pain, mostly located in the legs. 1 Radiographs show a symmetrical, bilateral, medullar sclerosis of the diaph- ysis of the long bones. 2 It is noteworthy that these radiographic findings were present in our patient even though bone pain was absent. Common additional symptoms are exophtalmos, due to the involvement of CPD (a) Figure 1 (a) Multiple papulonodular lesions on the trunk. Correspondence: Dr Vito Di Lernia, MD, Department of Dermatology, Arcispedale S. Maria Nuova, Viale Risorgimento 80, 42100 Reggio Emilia, Italy E-mail: vito.dilernia@asmn.re.it Conflict of interest: none declared. Accepted for publication 5 April 2009 CED Clinical and Experimental Dermatology Ó 2010 The Author(s) Journal compilation Ó 2010 British Association of Dermatologists • Clinical and Experimental Dermatology, 35, e187–e189 e187