Introduction: Melanoma, a malignant tumor arising from uncontrolled melanocytic proliferation, commonly found in the skin but capable of affecting extracutaneous sites, ranks fifth among diagnosed oncological entities and is a significant cause of cancer deaths, constituting over 80% of skin cancer mortality. Genetic factors and ultraviolet radiation (UVR) exposure, from both natural and artificial sources, are the primary risk factors. Case Presentation: We reported the case of a 25-year-old female with numerous pigmented nevi and notable changes attributed to extensive indoor tanning sessions. Dermatological examinations and dermoscopic evaluations revealed atypical features in two pigmented nevi, leading to surgical excision. Histopathological and immunohistochemical analyses confirmed a compound nevus in one lesion and superficial spreading melanoma in the other, emphasizing the importance of vigilant follow-up and the correct use of immunohistochemistry. Discussion: Indoor tanning significantly elevates the cutaneous melanoma risk, with initiation before age 35 amplifying the risk by up to 75%, especially in young women. The risk escalates with cumulative sessions, particularly exceeding 480, and individuals undergoing over 30 sessions face a 32% higher risk. UVR induces DNA damage, genetic mutations, and immunosuppression, contributing to oncogenesis. Genetic factors, like the PTCHD2 gene, may influence the tanning dependency. Legislation targeting minors has been enacted globally but only with partial efficacy. Tanning accelerators, though associated with minor side effects, correlate with high-risk behaviors. The case underscores the urgency of addressing indoor tanning risks, emphasizing targeted awareness efforts and legislative improvements. Conclusions: In conclusion, the reported case highlights the increased risk of cutaneous melanoma linked to indoor tanning, particularly among young women and specific sociodemographic groups. Despite legislative measures, challenges persist, suggesting the potential efficacy of online campaigns involving relatable influencers to raise awareness and discourage artificial tanning.

Appendiceal endometriosis is a rare entity and, when accompanied by intestinal metaplasia, represents a challenging differential diagnosis with low-grade appendiceal mucinous neoplasm (LAMN). We present the case of a 47 years-old woman, with multiple surgical interventions for endometriosis, with persistent symptoms despite chronic hormonal treatment, with imaging showing stage IV endometriosis. Hence, en bloc low rectum resection with total hysterectomy and bilateral adnexectomy was performed, followed by appendectomy. Unexpectedly, despite the gross normal macroscopic appearance of the appendix, microscopy showed multiple endometriosis foci, consisting of endometrial glands embedded in varying amounts of endometrial stroma. As some of these glands were bordered by mucinous-type epithelium containing intestinal cells, Goblet cells, Paneth cells in addition to the presence of mucus-filled microcysts, immunohistochemistry (IHC) was performed in order to differentiate between intestinal-metaplasia and LAMN. IHC showed positivity of the endometrial epithelium for KRT7, estrogen receptor (ER) and progesterone receptor (PR). Both the appendiceal mucosa and the intestinal-type metaplastic epithelium of the glandular structures were positive for KRT20. Additionally, the endometrial stroma enclosing endometrial glands, as well as the stroma surrounding mucinous-type metaplastic epithelium, were positive for CD10, ER and PR. This patient's case draws attention to the rare occurrence of appendiceal endometriosis and the uncommon intestinal metaplasia, which can easily mimic LAMN, emphasizing the paramount importance of the differential diagnosis with this type of neoplasia.