Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2022;12(3):e2022071 1 Dermatology Practical & Conceptual Unusual Presentation of Kaposi Sarcoma During Adalimumab Therapy: a Case Report Gulsun-Hazan Tabak1, Basak Yalici-Armagan1, Burkay-Adem Sahin1, Ozay Gokoz2, Sedat Kiraz3 1 Hacettepe University, School of Medicine, Department of Dermatology and Venereology, Ankara, Turkey 2 Hacettepe University, School of Medicine, Department of Pathology, Ankara, Turkey 3 Hacettepe University, School of Medicine, Department of Rheumatology, Ankara, Turkey Key words: psoriasis, biologics, kaposi sarcoma, TNF antagonist Citation: Tabak GH, Yalici-Armagan B, Sahin BA, Gokoz O, Kiraz S. Unusual Presentation of Kaposi’s Sarcoma During Adalimumab Therapy: A Case Report. Dermatol Pract Concept. 2022;12(3):e2022071. DOI: https://doi.org/10.5826/dpc.1203a71 Accepted: October 11, 2021; Published: July 2022 Copyright: ©2022 Tabak et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/ which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original authors and source are credited. Funding: None. Competing interests: None. Authorship: All authors have contributed significantly to this publication. Corresponding author: Basak Yalici-Armagan, MD, Hacettepe University, School of Medicine, Department of Dermatology and Venereology, 06100, Ankara, Turkey, Telephone: 00903123051704, Fax: 0 3123114340, E-mail: basakarmagan@gmail.com Introduction Kaposi sarcoma (KS) is a rare angioproliferative malignancy associated with Human Herpesvirus-8 (HHV-8) that in- volves skin and visceral organs. It typically manifests with magenta-colored macules, papules, and nodules on the skin. Herein, we present a patient who developed pyogenic granu- loma (PG)-like KS during adalimumab therapy for psoriatic arthritis. Case presentation A 48-year-old male applied to our dermatology outpatient clinic for a bleeding lesion on the right forth toe. The lesion occurred seven-months before and grew rapidly in last one- month. He has been diagnosed with psoriatic arthritis 4 years ago and treated with adalimumab, a tumor necrosis factor-α inhibitor (TNFi), for the last one year. Dermatological ex- amination revealed a 1cm x1 cm diameter of reddish, ulcer- ated, protruding hemorrhagic nodule partially covered with hyperkeratotic crust and fibrin just under the fourth toe nail (Figure 1, A and B). Excisional biopsy was performed with provisional diagnoses of amelanotic malignant melanoma, PG and cutaneous squamous cell carcinoma. Histopatho- logical examination showed nodular lesion in the dermis made up of atypical spindle shaped cells showing whorled structures and slit like spaces filled with erythrocytes. Im- munohistochemical examination indicated HHV-8 positivity and confirmed the diagnosis of KS (Figure 1E). In detailed dermatological examination, purple-colored patches on the lateral aspects of both feet were noticed (Figure 1, C and D). HIV serology was negative. Adalimumab treatment was ceased immediately and the patient was addressed to oncol- ogy department for remaining lesions. Conclusions The potential of TNFis to increase the risk of malignancy including melanoma and non-melanoma skin cancer is still controversial. Although iatrogenic KS has been described in 2 Research Letter | Dermatol Pract Concept. 2022;12(3):e2022071 Figure 1. (A, B) Reddish-purplish, firm, easy-bleed- ing nodule covered with hyperkeratotic crust and fibrine just under the right forth toe nail. (C, D) Pur- ple-colored patches on the lateral sides of both feet. (E) Spindle cells, slit like spaces and erythrocytes, HHV8 positivity (inlet) are shown in histopatho- logic examination (H&E x200). Research Letter | Dermatol Pract Concept. 2022;12(3):e2022071 3 organ transplant recipients receiving immunosuppressive therapy, there are only a few reports of KS during TNFi ther- apy that were presenting as typically purplish-red patches and papulonodular lesions on the lower leg [1]. Classic KS is typically seen in older men (64–72 years) of Mediterra- nean, Eastern European (Ashkenazi) Jewish, or South Amer- ican origin whereas endemic KS is limited to sub-Saharan Africa and is typically seen in young (25–40 years), black, HIV-negative men. On the other hand, KS and psoriasis spec- ulated to share common pathogenesis particularly related with interleukin-6 cytokine pathway or the same human leu- kocyte antigen alleles. Although we cannot explain the exact mechanism of this association whether it is a co-existence of KS and psoriasis or it is triggered by adalimumab, HIV negativity and the early age of onset compared to classical KS suggested a relationship with adalimumab in the present case. Unlike reported KS cases induced by TNFi treatment, PG-like presentation with classical purple-colored patches was a remarkable finding of the current case. PG-like KS is a rare variant of KS that is difficult to diagnose clinically [2]. We present this rare case of PG-like KS that can be easily confused with other skin tumors in a patient under biologic treatment. If characteristic purple-colored patches of KS on the lat- eral sides of feet were not overlooked on physical examina- tion in the current case, it could have been possible to include KS in the clinical pre-diagnoses. Detailed whole body skin examination is crucial for dermatologists to provide correct clinical diagnosis for early management. Further evidence is needed to clarify the relationship between biologics and ma- lignancy development. References 1. Ursini F, Naty S, Mazzei V, Spagnolo F, Grembiale RD. Kaposi’s sarcoma in a psoriatic arthritis patient treated with infliximab. Int Immunopharmacol. 2010;10(7):827-828. DOI: 10.1016/j.intimp.2010.04.016. PMID: 20433950. 2. Megaly M, Boshra N. Pyogenic granuloma-like Kaposi’s sar- coma. Lancet. 2022;399(10335):e38. DOI: 10.1016/S0140- 6736(15)00467-5. PMID: 26498707.