Extraordinary Case ReportFibroblastic Rheumatism Versus Variant Disease of Multinucleate Cell AngiohistiocytomaCai, Sophie Carrie Shan MD, MRCP (UK); Tee, Shang Ian MBBS, MRCP (UK), FRCP (London), FAMS (Dermatology), Dip Dermatopathology (ICDP-UEMS); Lee, Joyce Siong See MBBS, MRCP (UK), MMed (Int Med), FAMS (Dermatology), Dip Dermatopathology (ICDP-UEMS); Tan, Lucinda Siyun MBBS, MRCP (UK), MMed (Int Med)Author Information National Skin Centre, Singapore. Correspondence: Lucinda Siyun Tan, MBBS, MRCP (UK), MMed (Int Med), Department of Dermatology, National Skin Centre, Singapore, National Skin Centre, 1 Mandalay Road, Singapore 308205, Singapore (e-mail: [email protected]). The authors declare no conflicts of interest. The American Journal of Dermatopathology: February 2020 - Volume 42 - Issue 2 - p 136-139 doi: 10.1097/DAD.0000000000001550 Buy Metrics Abstract We report an unusual case of a 49-year-old woman who presented with persistent papulonodules over bilateral fingers and inframammary region in conjunction with features of connective tissue disease including symmetrical polyarthritis and Raynaud phenomenon. Skin biopsy showed an upper-to-mid dermal proliferation of bland spindled cells with thickened collagen bundles and occasional multinucleated giant cells. Dermal blood vessels were only marginally increased. On immunohistochemistry, both the spindled cells and multinucleated giant cells stained negatively for smooth muscle actin. Some of the spindled cells stained positively with CD68 and CD163, whereas the multinucleated giant cells stained negatively for both stains. Elastic fibers were absent on elastic Van Gieson. The clinical and histopathologic features raise a diagnostic dilemma between fibroblastic rheumatism and multinucleate cell angiohistiocytoma. The patient responded well to cyclosporine and methotrexate therapy, with gradual improvement of the finger nodules. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.