Dermatology: Practical and Conceptual Research Letter | Dermatol Pract Concept. 2022;12(1):e2022023 1 Umbilical Endometriosis: A New Dermoscopic Pattern Jorge Juan Vega-Castillo1, Soledad Saenz-Guirado1, Maria Luisa Vega-Castillo2, Ricardo Ruiz-Villaverde1 1 Dermatology Department, Hospital Universitario San Cecilio, Granada, Spain 2 Ophtalmology Department, Hospital de Alta Resolución de Écija, Spain Key words: endometriosis, pattern, dermoscopy Citation: Vega-Castillo JJ, Saenz-Guirado S, Vega-Castillo M, Ruiz-Villaverde R. Umbilical endometriosis: a new dermoscopic pattern. Dermatol Pract Concept. 2022;12(1):e2022023. DOI: https://doi.org/10.5826/dpc.1201a23 Accepted: June 10, 2021; Published: January 2022 Copyright: ©2022 Vega-Castillo et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License 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: Ricardo Ruiz-Villaverde, Unidad de Dermatología. Hospital Universitario San Cecilio, Granada, Spain. E-mail: ismenios2005@gmail.com Introduction Endometriosis is defined as the growth of ectopic endometrial tissue outside the uterine cavity. Extra pelvic endometriosis occurs in 12% of women, and umbilical endometriosis, a rare presentation of extra pelvic endometriosis, occurs in 0.5%-1% of reported cases. Umbilical endometriosis is also known as Villar nodule as Villar first described the condition in 1886. Cutaneous endometriosis tends to settle on scars from surgical procedures (abdominal or pelvic surgery) such as hysterectomy, caesarean section, laparoscopy, or episiotomy. From a clinical point of view, it is necessary to establish a differential diagnosis with amelanotic melanoma, basal cell carcinoma, Sister Mary Joseph nodule, or pyogenic granuloma. Case Presentation A 45-year-old woman attended our dermatologic outpatient clinic complaining of a 4-months history of a solitary painless umbilical nodule. The bluish-green colored lesion had not appeared on a previous scar. Any recent bleeding episode was ruled out. A complete medical history revealed long- term dysmenorrhea as the only relevant clinical finding. On dermoscopy, a central white reticular pattern on a violet background was observed (Figure 1A). No vascular struc- tures, points, globules, or structures suggestive of a melano- cytic lesion were observed. Histopathological examination was consistent with cutaneous endometriosis (Figure 1B). Complementary tests, including abdominal-pelvic CT and determination of cancer antigen 125 offered results within normal ranges. Conclusions There are few dermoscopic descriptions in the literature of cutaneous endometriosis [1,2]. The main dermoscopic find- ings and histopathological correlation are reflected in Table 1. There appears to be a difference in patterns depending on the phase of the hormonal cycle, as well as the depth of the lesion, histological subtype and phototype of the patient. 2 Research Letter | Dermatol Pract Concept. 2022;12(1):e2022023 Table 1. Dermoscopic Descriptions of Umbilical Endometriosis Authors Dermatoscope Model Dermoscopic Features Interpretation Polarized Mode De Giorgi, 2003 [3] Heine-10 Homogeneous reddish pigmentation, regularly distributed, gradually fading to the periphery Small red globular structures (red atolls) Multiple irregular glands with erythrocytes in a myxoid vascular stroma Non-polarized Jerez-Jaime, 2013 [4] DermLite II Pro HR Homogeneous reddish localized pigmentation, with no differentiated structures Amorphous brown area with normal skin network Myxoid vascular stroma Polarized light dermoscopy Costa, 2014 [5] DermLite DL3, Polypoid projections of erythematous violaceous color, area with dark brown globules and area of active bleeding (mid follicular phase) Increased in both characteristics (luteal phase) Endometrial atrophy Hemoglobin degradation after bleeding period, corresponding to hemosiderin deposits Polarized light dermoscopy Bonné, 2020 [2] DermLite DL4 Umbilical endometriosis (polypoid structure) with drainage openings Multiple irregular glands with erythrocytes and drainage openings Polarized light dermoscopy Sandoval, 2021 [6] Unknown Pink homogeneous lesion with a focal bluish blotch/clod Hemosiderin deposits Polarized light dermoscopy White reticular pattern (negative pigment network) is due to elongated rete ridges and is characteristic of melanoma. Nevertheless, it has also been observed in Spitz/Reed nevi. The diffuse area of bluish color is likely related to hemosiderin deposits, unlike the referred deposits observed in other cases reported as small focused globules. Histopathological examination remains the diagnostic gold standard for endometriosis. It is considered mandatory in ruling out a neoplastic condition, as more than 60% of umbilical tumors are malignant. The description of new der- moscopic patterns and their histological correlations can be helpful in the diagnosis of this entity. Informed consent: Informed consent for publication of clini- cal details and clinical images was obtained from the patient. References 1. Boesgaard-Kjer D, Boesgaard-Kjer D, Kjer JJ. Primary umbil- ical endometriosis (PUE). Eur J Obstet Gynecol Reprod Biol. 2017;209:44–45. 44-45. DOI: 10.1016/j.ejogrb.2016.05.030. PMID: 27374811. 2. Bonné E, Daxhelet M, Simon P, Del Marmol V, Suppa M. The pe- culiar dermoscopic features of primary umbilical endometriosis. J Eur Acad Dermatol Venereol. 2020;34(10):e589-e591. DOI: 10.1111/jdv.16455. PMID: 32277548. Figure 1. (A) Polarized dermoscopy shows central white reticular pattern (blue arrow) on a violet background (blue star) (DermLite DL4, ×10). (B) Histopathology shows positivity for progesterone-receptor markers in endometrial glands and stroma (immunohis- tochemistry: anti-progesterone receptor antibodies; original magnification, ×100). Research Letter | Dermatol Pract Concept. 2022;12(1):e2022023 3 3. De Giorgi V, Massi D, Mannone F, Stante M, Carli P. Cutane- ous endometriosis: non-invasive analysis by epiluminescence microscopy. Clin Exp Dermatol. 2003;28(3):315-7. DOI: 10.1046/j.1365-2230.2003.01194.x. PMID: 12780722. 4. Jaime TJ, Jaime TJ, Ormiga P, Leal F, Nogueira OM, Rodrigues N. Umbilical endometriosis: report of a case and its dermoscopic features. An Bras Dermatol. 2013;88(1):121-4. DOI: 10.1590/ s0365-05962013000100019. PMID: 23539017; PMCID: PMC3699952. 5. Costa IM, Gomes CM, Morais OO, Costa MC, Abraham LS, Argenziano G. Cutaneous endometriosis: dermoscopic findings related to phases of the female hormonal cycle. Int J Dermatol. 2014;53:e130-2. DOI: 10.1111/j.1365-4632.2012.05854.x. PMID: 23621541 6. Sandoval M, Meza-Romero R, Peñailillo A, Villaseca MÁ, Navarrete-Dechent C. Dermoscopy findings of umbilical endometriosis. Australas J Dermatol. 2021;62(1):e139-e141. DOI: 10.1111/ajd.13437. PMID: 32909620.