Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2022;12(3):e2022083 1 Dermatology Practical & Conceptual A Case of Adult-onset Facial Cutaneous Mastocytoma: Clinical and Dermoscopic Findings Matteo Megna1, Massimiliano Scalvenzi1, Sonia Sofía Ocampo Garza1,2, Gabriella Fabbrocini1, Elisa Camela1 1 Section of Dermatology - Department of Clinical Medicine and Surgery, University of Naples Federico II, Naples, Italy 2 Universidad Autónoma de Nuevo León, University Hospital ¨Dr. José Eleuterio González¨, Dermatology Department, Monterrey, Nuevo León, México Key words: solitary mastocytoma, adult, cutaneous mastocytoma, mastocytosis, facial Citation: Megna M, Scalvenzi M, Ocampo Garza SS, Fabbrocini G, Camela E. A case of adult-onset facial cutaneous mastocytoma: clinical and dermoscopic findings. Dermatol Pract Concept. 2022;12(3):e2022083. DOI: https://doi.org/10.5826/dpc.1203a83 Accepted: October 17, 2021; Published: July 2022 Copyright: ©2022 Megna 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: Elisa Camela, MD, Department of Dermatology, University of Naples Federico II, Via Pansini, 5 80131 Napoli, Italy, Tel: +39 - 081 -7462457 Fax: +39 - 081 – 7462442, E-mail: elisacamela@gmail.com Introduction Cutaneous mastocytoma is a form of mastocytosis that usu- ally affects newborns and children, representing an uncom- mon finding in adults [1]. Clinically, it presents with up to 3 yellowish, brown, or red nodular lesions mainly located on the trunk and extremities [1]. The most common dermo- scopic feature is a yellow-orange blot pattern [1]. We report the unusual case of an adult-onset facial cuta- neous mastocytoma, arising on the forehead, and describe a new dermoscopic pattern. Case presentation A 36-year-old woman came to our dermatology department for the presence of an asymptomatic erythematous plaque on the forehead, of two-month-duration (Figure 1). The patient was in good health and did not refer systemic symptoms; her medical and pharmacological history was unremarkable. Dermoscopic evaluation revealed an irregular vascular pat- tern characterized by irregular linear vessels, some of which serpiginous, of steady caliber, on a pink-red background and perifollicular scar-like white areas (Figure 2). Incisional biopsy displayed the presence of a diffuse and homogeneous pan-dermal infiltrate of mast cells, with some perivascu- lar and peri-adnexal lymphocytes and plasma cells in the upper dermis. To rule out systemic mastocytosis, routine blood tests as well as serum tryptase (sT) were performed resulting unremarkable. Based on clinical, dermoscopic and histologic findings along with normal sT levels and absence of systemic involvement, a diagnosis of cutaneous mastocy- toma was made. The patient was started on topical tacro- limus with progressive subsiding of clinical manifestations. Conclusions Adult-onset cutaneous mastocytoma is a rare entity de- scribed in less than 20 patients so far [1]. Its diagnosis is 2 Research Letter | Dermatol Pract Concept. 2022;12(3):e2022083 Figure 1. Clinical aspect of facial cutaneous mastocytoma: an erythematous plaque of the forehead. Figure 2. Dermoscopy of facial cutaneous mastocytoma: irregular vascular pattern with linear vessels, some of which serpiginous, showing steady caliber; pink-red background; perifollicular scar-like white areas. Research Letter | Dermatol Pract Concept. 2022;12(3):e2022083 3 challenging as it may be confused with a vast spectrum of diseases according to its clinical presentation. Indeed, it may appear as a macule, papule, plaque or nodule and vary in color from yellow to brown, to red [2]. Dermoscopically, cutaneous mastocytoma has been reported to present a yellow-orange blot pattern [2]. Anyway, in our case, an ir- regular vascular pattern exclusively characterized by irreg- ular linear and serpiginous vessels of steady caliber, on a pink-red background and perifollicular scar-like white areas were observed. More data are needed since reported der- moscopic descriptions are very scant. Given that the onset of cutaneous mastocytosis in adults is frequently associated with systemic disease, it has been recommended that the ini- tial diagnostic work-up should include blood tests ( complete blood cell count, serum chemistries with liver function tests, and sT levels), and also bone marrow biopsy (BMB) [2]. If there is no systemic involvement, all the above-mentioned in- vestigations apart from BMB, should be repeated yearly [2]. In our case, due to the absence of systemic symptoms and normal sT, BMB was not performed. Concerning treatment, surgical excision is the most employed one, followed by topi- cal or intralesional corticosteroids [2]; other treatments com- prise pimecrolimus and pulsed dye laser therapy [2]. We reported the unusual case of adult-onset facial masto- cytoma, arising on the forehead, and described new dermo- scopic findings. Although the strength of our observation is limited by the single patient, we believe that enriching litera- ture with new information may contribute to improve diag- nosis of unusual manifestations. Informed consent: Written informed consent was obtained from the patient for publication of this case report and any accompanying images. References 1. Vano-Galvan S, Álvarez-Twose I, De Las Heras E, et al. Dermo- scopic features of skin lesions in patients with mastocytosis. Arch Dermatol. 2011;147(8):932-940. DOI:10.1001/archdermatol. 2011.190. PMID: 21844452. 2. Cohen P. Solitary mastocytoma presenting in an adult: report and literature review of adult-onset solitary cutaneous mastocytoma with recommendations for evaluation and treatment. Dermatol Pract Concept. 2016;6(3):31-38. DOI:10.5826/dpc.0603a07. PMID: 27648381. PMCID: PMC5006550.