Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2023;13(2):e2023086 1 Unicentric Castleman Disease in the Temporal Region of a Pediatric Patient Jeffrey Dickman1, Samantha Haraszti1, Karen Warschaw1,2, Weimin Hu1,3 1 Kansas City University (KCU-GMEC) Phoenix Dermatology, Phoenix, Arizona, United States 2 Sonic Healthcare USA, Arizona Dermatopathology, Scottsdale, Arizona, United States 3 Specialists in Dermatology, Tucson, Arizona, United States Key words: Castleman disease, pediatric, temple, lymphoproliferative disorders Citation: Dickman J, Haraszti S, Warschaw K, Hu W. Unicentric Castleman Disease in the Temporal Region of a Pediatric Patient. Dermatol Pract Concept. 2023;13(2):e2023086. DOI: https://doi.org/10.5826/dpc.1302a86 Accepted: September 13, 2023; Published: April 2023 Copyright: ©2023 Dickman et al. This is an open-access article distributed under the terms of the Creative Commons Attribution- NonCommercial 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: Jeffrey Dickman, DO, 4801 E McDowell Rd, STE 150, Phoenix, Arizona 85008, United States. 602-954-3919 E-mail: jstdickman@gmail.com Introduction Castleman disease (CD) encompasses a group of rare lymph- oproliferative disorders with common histopathologic fea- tures. The most common subtype is unicentric CD (UCD) which involves a single region of enlarged lymph nodes. CD can occur in any lymph node; however, CD has a predilec- tion for the mediastinum, and rarely presents on the face [1]. Here we report a case of UCD presenting in the temporal region of a pediatric patient. Case Presentation An 11-year-old female presented for excisional biopsy of an enlarging mass on the right temple which had been present for 17 months and was occasionally tender. An MRI revealed a well-circumscribed 3.4 cm x 1.4 cm x 3 cm soft tissue mass lateral to the temporalis muscle. Histological analysis of the specimen revealed lymphoid tissue with atretic and hyalinized germinal centers, concentric laminations resulting in an “onion-skin appearance,” and penetrating hyalinized arterioles (Figure 1). Immunohisto- chemistry demonstrated CD20 and PAX-5 positive B cells Figure 1. Lymphoid tissue with atretic and hyalinized germinal cen- ters, concentric laminations resulting in an “onion-skin appearance,” and penetrating hyalinized arterioles (H&E, 40x). 2 Research Letter | Dermatol Pract Concept. 2023;13(2):e2023086 within the germinal centers, as well as CD21 positive fol- licular dendritic cells forming a laminated meshwork and occasionally merging with neighboring germinal centers. These findings in a single region, along with the absence of prominent plasmacytosis, atypical lymphocytes, and large or transformed lymphoid populations are consistent with the features of UCD. Conclusions CD is categorized into two groups: unicentric and mul- ticentric. UCD involves a single region of enlarged lymph nodes and is more common than multicentric CD (MCD). MCD affects multiple lymph node regions and usually presents with systemic symptoms or laboratory abnormal- ities demonstrating chronic inflammation such as elevated C-reactive protein [2]. There are three major histological subtypes of CD: hyaline-vascular CD (HV-CD), plasma cell CD (PC-CD) and a mixed histopathologic subtype. Over half of UCD cases demonstrate the hyaline-vascular CD morphology, whereas MCD more often demonstrates the plasma cell variant [3]. UCD is typically asymptomatic and often discovered as an incidental finding on imaging or physical examination; however, it can also present with mass effect on neighbor- ing structures [3,4]. UCD in the pediatric population is most commonly found within the mediastinum [4]. A complete resection of the lymphoid tissue is almost al- ways curative for UCD. It is unknown if UCD in the tempo- ral region carries a distinct prognosis from other locations, however, the prognosis following complete resection of UCD affecting a peripheral lymph node is significantly better than UCD in the chest or abdominal cavities. In a systematic re- view of 278 UCD cases, 249 had surgical resection alone, and 13 had combination surgical and immunosuppressive treatments with a 5-year disease free recurrence rate of ap- proximately 81% and a 10-year survival rate of approxi- mately 95%. Continued follow-up is essential to monitor for recurrences. Treatment of MCD is more complex and the prognosis is generally worse with a 10-year survival rate of approximately 67% [5]. There have been two other case reports of CD presenting in the temporal region [1,3]. This case is unique given the presentation of temporal UCD in a pediatric patient. Derma- tologists should be aware that CD may develop in this region in both children and adults. References 1. Kang N, Chung J, Jung S. Rare Location of Castleman Disease in the Temporal Region. J Craniofac Surg. 2009;20(3)830-2. DOI: 10.1097/SCS.0b013e3181a14c19. PMID: 19349907. 2. Dispenzieri A, Fajgenbaum DC. Overview of Castleman disease. Blood. 2020;135(16):1353-1364. DOI: 10.1182/ blood.2019000931. PMID: 32106302. 3. Ryu W, Park MH, Kim H, Koh IC, Kim KN. Rare Location of Castleman’s Disease in the Temporal Region: A Case Report Involving a Young Korean Woman and Review of the Litera- ture. Arch Craciofac Surg. 2017;18(2)122-127. DOI: 10.7181/ acfs.2017.18.2.122. PMID: 28913319. PMCID: PMC5556893. 4. Wala S, Fallon E, Forlenza C, Shukla N, LaQuaglia M. Unicentric Castleman disease in the mediastinum. J Pediatric Surg Case Reports. 2018;34:51-53. 5. Talat N, Belgaumkar AP, Schulte KM. Surgery in Castleman's disease: a systematic review of 404 published cases. Ann Surg. 2012 Apr;255(4):677-84. DOI: 10.1097/SLA.0b013e318249d- cdc. PMID: 22367441.