A case report of multicentric reticulohistiocytosis with atypical cutaneous presentation

Abstract

Multicentric reticulohistiocytosis (MRH) is a rare systemic disorder characterized by histiocytic hyperplasia that mainly involves the skin, mucous membranes, and joints. The typical clinical features include papules, nodules, and arthritis. MRH lesions are relatively extensive but small and scattered. Joint inflammation is characterized by diffuse symmetric polyarthritis as the first symptom, which can be severe and disabling due to destructive joint changes. MRH is easily misdiagnosed in clinical practice. Here, we report the case of an elderly male patient who presented with polyarticular pain in the hip and interphalangeal joints as the first manifestation, followed by the development of large, isolated, bulging skin nodules, which are atypical MRH lesions. This is rare in all MRH case reports, and we made the correct diagnosis by combining skin histopathology, immunohistochemistry, and other clinical examinations. We performed surgical treatment on the local skin lesions of this patient. This case suggests that clinicians should actively correlate the condition and accurately diagnose MRH when encountering atypical skin changes or other diseases as the first symptom and explore the mechanisms of MRH and other clinical manifestations.

Keywords: differential diagnosis; gouty arthritis; immunohistochemistry; multicentric reticulohistiocytosis; nodular xanthomatosis.

Figure 1

Skin changes and imaging in the patient with multicentric reticulohistiocytosis. (A) Skin lesions in the right inguinal region. (B) Mild swelling of the interphalangeal joints of both fingers of the patient, with no obvious deformation. (C) Mild bony changes at the edges of the interphalangeal joints indicated by the red arrow on the X-ray, and mild narrowing of the interphalangeal joint space. (D) MR scan of the sacroiliac joint, with the red arrow indicating lipid deposition in the hip joint. (E) MR scan of the sacroiliac joint, with the red arrow indicating lipid deposition in the hip joint. (F) Pelvic X-ray, with the red arrow indicating degenerative changes in the hip joint with decreased cystic density.

Figure 2

Histopathology and immunohistochemistry of the dermis of the patient with multicentric reticulohistiocytosis. (A) Mild atrophy of the epidermis, with a large number of histiocytes in the dermis, locally foamy (HE × 100). (B) Diffuse histiocyte infiltration in the dermis, accompanied by a large number of multinucleated giant cells in a “hairy glass”-like pattern, which is indicated with a red arrow (HE × 200). (C–J) Immunohistochemical staining for CD68 (diffuse +), vimentin (diffuse +), CD31 (diffuse +), and Vimentin (diffuse +). CD68 (diffuse +), vimentin (diffuse +), CD31 (diffuse +), LCA (CD45) (+), S-100 (−), CD1a (−), CD34 (−), and Ki-67 positivity of approximately 5%–10% (× 200).

Figure 3

Schematic diagram of the clinical course of the patient.