Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2023;13(3):e2023176 1 Rosettes: An Additional Clue for the Identification of the Primary Cutaneous Marginal Zone Lymphoma Maria Eugenia Gil1, Rosario Peralta2, Maria Cecilia Laporta1, Jimena Lorenzo1, María Mercedes Nusshold1 1 School of Medicine, University of Buenos Aires, Argentina 2 Dermatology Department, Instituto de Investigaciones Médicas “A. Lanari”, University of Buenos Aires, Argentina Key words: rosettes, lymphoma, primary cutaneous marginal zone lymphoma, dermoscopy Citation: Gil ME, Peralta R, Laporta MC, Lorenzo J, Nusshold MM. Rosettes: An Additional Clue for the Identification of the Primary Cutaneous Marginal Zone Lymphoma. Dermatol Pract Concept. 2023;13(3):e2023176. DOI: https://doi.org/10.5826/dpc.1303a176 Accepted: March 1, 2023; Published: July 2023 Copyright: ©2023 Gil 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: Maria Eugenia Gil, MD, Paraguay 2155, Ciudad Autónoma de Buenos Aires, Argentina. Tel: (+54) 011-61562798, E-mail: meugenia@fmed.uba.ar Introduction Primary cutaneous marginal zone lymphoma (PCMZL) is a B-cell lymphoma arising in the skin and accounts for a low incidence of all primary cutaneous lymphomas (2-7%) [1]. Dermoscopic features that have been described are salmon-colored area/background, serpentine vessels, scales and white circles [2]. Rosettes are a specific form of a white shiny structure seen with polarized dermoscopy [3]. We re- port a case showing multiple rosettes on PCMZL. Case Presentation A 36-year-old male patient presented an 8-month history of an enlarging asymptomatic lesion on his lower back. Physical examination showed a well-defined, indurated, reddish plaque measuring 1 x 2 cm. Dermoscopy revealed salmon-colored area/background, serpiginous vessels, and multiple rosettes (Figure 1). Neither adenopathies nor other lesions were palpated in the rest of the tegument. The histopathological examination presented preserved epidermis and a dense dermal lymphoid infiltration, which was arranged in a nodular pattern. The im- munohistochemistry was characterized by the expansion of the marginal zone cellular population BCL 2 + and CD 20 +. Nodal lymphocytes were CD3 - and peripheral lymphoid population was CD3+ (Figure 2). The diagnosis was PCMZL. A blood test was performed, with normal values: hemogram, hepatogram, urine and cre- atinine, beta two microglobulin assay, lactate dehydrogenase (LDH) and serological test for Epstein Barr Virus (EBV) and Cytomegalovirus (CMV). The computed tomography (CT) evaluation displayed no other lesions and the surgical exci- sion with 2 cm of diameter was performed. 2 Research Letter | Dermatol Pract Concept. 2023;13(3):e2023176 Figure 1. (A-B) Clinical presentation of a well-defined, indurated, reddish plaque measuring 1 x 2 cm on lower back (white circle). (C) Polarized dermoscopy shows a salmon-colored background with serpiginous vessels (black circle) and multiple rosettes (arrows) of different sizes. Figure 2. Histopathological analysis.  (A) Dense dermal lymphoid infiltrate which was arranged in a nodular pattern (H&E, ×10). (B) Preserved epidermis (H&E, ×40). (C) CD3 – nodal lymphocytes/CD3 + peripheral lymphoid population. (D) BCL2 +. (E) CD 20+. Conclusions Rosettes are defined as 4 bright white circles arranged as a square resembling a 4-leaf clover, mainly localized in the follicular openings. Despite being well-described der- moscopically, the precise histology correlation and optical significance are not known. There are different types that would be caused by the interaction of keratin-filled adnexal openings with the polarized light: smaller ones (0.1-0.2 mm), usually oriented at the same angle, and larger ones that would be the result of concentric fibrosis around the follicles (0.2-0.5 mm) [3]. Research Letter | Dermatol Pract Concept. 2023;13(3):e2023176 3 They have been characteristically described in actinic keratosis and squamous cell carcinoma. However, they were commonly seen in non-lesional actinic damaged skin, scars, many tumoral and inflammatory skin lesions and hence are not lesion specific. Related to cutaneous lymphoproliferative disorders there are isolated reports of their presence in T-cell pseudolym- phoma and classic Mycosis Fungoides in patients with skin of color [4-5]. The dermoscopic findings of primary cutaneous B-cell lymphomas are not specific, characterized by salmon-colored background/area, serpentine vessels, scales and white circles [6]. Considering that the size of the rosettes can vary, we noticed in our case multiple small rosettes like targeted follicles instead of white circles. Both signs could be a pro- gression of the same feature [3]. Differential diagnosis of PCMZL is wide, including be- nign and malignant diseases. They are frequently misdiag- nosed as inflammatory and infectious lesions or as other cutaneous neoplasms such as basal cell carcinoma or amel- anotic melanoma. Diagnosis of PCMZL may be challenging and histopatho- logical examination is mandatory for a definite diagnosis. Dermoscopy could play an adjuvant role in the achievement of the diagnosis. This case provides an additional clue for its identification. References 1. Vitiello P, Sica A, Ronchi A, Caccavale S, Franco R, Argenziano G. Primary Cutaneous B-Cell Lymphomas: An Update. Front Oncol. 2020;10:651. DOI: 10.3389/fonc.2020.00651. PMID: 32528871. PMCID: PMC7266949. 2. Geller S, Marghoob AA, Scope A, Braun RP, Myskowski PL. Dermoscopy and the diagnosis of primary cutaneous B-cell lym- phoma. J Eur Acad Dermatol Venereol. 2018;32(1):53-56. DOI: 10.1111/jdv.14549. PMID: 28846171. PMCID: PMC5773353. 3. Peralta R, Salerni G, Sabban EC, Marin MB, Cabo H. Dermoscopy of a Squamous Cell Carcinoma of the Lower Lip Showing Mul- tiple Rosettes. Dermatol Pract Concept. 2019;10(1):e2020022. DOI: 10.5826/dpc.1001a22. PMID: 31921509. PMCID: PMC6936628. 4. Alves RG, Ogawa PM, Enokihara MMSES, Hirata SH. Rosettes in T-cell pseudolymphoma: a new dermoscopic finding. An Bras Dermatol. 2021;96(1):68-71. DOI: 10.1016/j.abd.2020.05.010. PMID: 33288369. PMCID: PMC7838094. 5. Nakamura M, Huerta T, Williams K, Hristov AC, Tejasvi T. Dermoscopic Features of Mycosis Fungoides and Its Vari- ants in Patients with Skin of Color: A Retrospective Analysis. Dermatol Pract Concept. 2021;11(3):e2021048. DOI: 10.5826 /dpc.1103a48. PMID: 34123556. PMCID: PMC8172036. 6. Piccolo V, Russo T, Agozzino M, et al. Dermoscopy of Cuta- neous Lymphoproliferative Disorders: Where Are We Now? Dermatology. 2018;234(3-4):131-136. DOI: 10.1159/000490412. PMID: 30032152. Table 1. Dermoscopy findings of primary cutaneous B-cell lymphoma. Dermoscopy findings of primary cutaneous B-cell lymphoma Salmon-colored background area Arborizing /Serpentine vessels Scales White circles Rosettes