Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2024;14(4):e2024222 1 Cutaneous Leiomyoma Mimicking Molluscum Contagiosum Maria Pia Boccellino1, Carmine Fiorentino1, Luigi Rossiello2, Amalia Lupoli1, Giuseppe Argenziano1, Andrea Ronchi3, Stefano Caccavale1 1 Dermatology Unit, Department of Mental and Physical Health and Preventive Medicine, University of Campania Luigi Vanvitelli, Naples, Italy 2 Department of Dermatology, A.O.R.N. “A. Cardarelli”, Naples, Italy 3 Pathology Unit, Department of Mental and Physical Health and Preventive Medicine, University of Campania Luigi Vanvitelli, Naples, Italy Key words: cutaneous leiomyoma, molluscum contagiosum Citation: Boccellino MP, Fiorentino C, Rossiello L, et al. Cutaneous Leiomyoma Mimicking Molluscum Contagiosum. Dermatol Pract Concept. 2024;14(4):e2024222. DOI: https://doi.org/10.5826/dpc.1404a222 Accepted: June 24, 2024; Published: October 2024 Copyright: ©2024 Boccellino 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 Pia Boccellino, Dermatology Unit, University of Campania Luigi Vanvitelli, Nuovo Policlinico (edificio 9C), Via Pansini 5, 80131, Naples, Italy, tel: +39 3281821432, E-mail: boccellino.mariapia@gmail.com Introduction Cutaneous leiomyomas are benign, often painful, neoplasms arising from the smooth muscle [1]. The main differential diagnosis includes other painful cutaneous lesions such as angiolipoma, neuroma, blue rubber bleb nevus, cutaneous endometriosis, glomus tumor, and granular cell tumor [2]. We present a case of a cutaneous leiomyoma misdiagnosed as molluscum contagiosum. Case Presentation In March 2023, a 23-year-old man presented to our atten- tion for a newly growing lesion on his left thigh. On clinical examination, the lesion showed a translucent aspect, with a mild central depression and hard elastic consistency at pal- pation (Figure 1A). At dermoscopy, the lesion appeared as a smooth pink papule covered with fine scales in the center. Peripherally, a circular brownish structureless area and some glomerular vessels were detected (Figure 1B). The patient referred the zone around the papule to be mildly painful when touched, and sensitive especially after exposure to cold temperatures. When asked about the onset of this lesion, the patient told us that it had appeared for the first time almost a year before (January 2022). Since then, it had showed no signifi- cant growth or symptoms, leaving the patient unconcerned. He sought a dermatologist’s attention only after some months, in November 2022. The first dermatologist made a diagnosis of molluscum contagiosum and treated this pap- ule with curettage. After four months, the lesion grew back, showing the exact same features it had had prior to the cu- rettage, and the patient presented to our clinic to be visited by another specialist. At this point, given the history of recurrence of the le- sion, and a clinical/dermoscopic uncertainty, an excisional 2 Research Letter | Dermatol Pract Concept. 2024;14(4):e2024222 biopsy with histopathological report was planned, with the clinical suspicion of an adnexal or mesenchymal tumor. The histopathological examination revealed a neoplasm located in superficial and deep dermis. The dermal neoplastic pro- liferation was arranged in interlacing bundles (Figure 2A). Spindle-shaped neoplastic cells were present, with eosino- philic cytoplasm and oval nuclei; collagen fibers were inter- mingled (Figure 2B). The neoplastic cells stained positive for smooth-muscle actin immunohistochemistry (Figure 2C). All these findings, according to morphological data, suggested the diagnosis of leiomyoma, excluding that of leiomyosarcoma and the original hypothesis of molluscum contagiosum. A short 4-month follow-up was then planned to exclude a new recurrence of the lesion or the appearance of other leiomyomas in different body sites. Conclusions This case illustrates the clinical challenge of managing sol- itary pink papules/ nodules. Even though the dermoscopy and clinical image of this case lesion could lead to suspect- ing a molluscum contagiosum, the symptoms reported by the patient could have helped the clinician not to miss this diagnosis. Given the usual presence of its associated symp- tomatology, leiomyoma is not usually considered among the differential diagnosis of molluscum contagiosum [3]; however, in the literature there are reported cases of misdi- agnosed leiomyomas with other asymptomatic lesions like keloids [4]. An interventional approach through shaving/ excisional biopsy with a histopathological report should al- ways be considered, especially in adults presenting with sol- itary pink papules. Figure 1. (A) Clinical picture of the lesion showing a translucent pink papule with a mild central depression. (B) Dermoscopic image shows a pink papule covered with fine scales in the center. Peripherally, a circular brownish structureless area and some glomerular vessels are visible. Research Letter | Dermatol Pract Concept. 2024;14(4):e2024222 3 References 1. Marcoval J, Llobera-Ris C, Moreno-Vílchez C et al. Cutaneous Leiomyoma: A Clinical Study of 152 Patients. Dermatology. 2022;238(3):587-593. doi: 10.1159/000518542. Epub 2021 Sep 23. PMID: 34569484. 2. Bhat MR, George AA, Jayaraman J. Painful tumors of the skin - from ENGLAND to LEND AN EGG to BLEND TAN EGG. Indian J Dermatol Venereol Leprol. 2019 Mar-Apr;85(2):231-234. doi: 10.4103/ijdvl.IJDVL_1165_16. PMID: 30289111. Figure 2. (A) A poorly demarcated dermal neoplastic proliferation arranged in interlacing bundles; a pilar muscle is present on the left side (hematoxylin and eosin stain, original magnification 40x). (B) Neoplastic cells are spindle-shaped, with eosinophilic cytoplasm and oval nuclei; collagen fibers are intermingled (hematoxylin and eosin stain, original magnification 200x). (C) The neoplastic cells stained positive for smooth-muscle actin immunohistochemistry (immunohistochemical stain, original magnification 200x). 3. Meza-Romero R, Navarrete-Dechent C, Downey C. Molluscum contagiosum: an update and review of new perspectives in etiology, diagnosis, and treatment. 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