Background: Solar urticaria is a rare and disabling photodermatosis. Due to its low prevalence, most available data regarding treatment are derived from observational studies and case series, and a systematic evaluation of treatment efficacy is lacking. This systematic review and meta-analysis aims to assess therapeutic outcomes across treatment modalities in order to guide clinical care. Methods: We conducted a systematic literature search across PubMed, ScienceDirect, the Cochrane Library, and ClinicalTrials.gov. Studies reporting treatment outcomes in patients with solar urticaria were included. Pooled response rates were calculated for each treatment modality. Results: Out of 508 studies initially identified, 38 met the inclusion criteria. Antihistamines were evaluated in 21 studies (376 patients), with a pooled response rate (partial or complete) of 83.0% (95% CI, 70.4–91.1%) and a complete response rate of 7.7% (95% CI, 1.7–28.3%). Phototherapy was assessed in 11 studies (145 patients), showing a similar overall response (89.8%; 95% CI, 77.9–95.3%) but a higher complete response rate (39.8%; 95% CI, 18.3–66.1%). Omalizumab, evaluated in nine studies (76 patients), demonstrated the highest efficacy, with 93.2% (95% CI, 73.8–98.5%) achieving response and 68.4% (95% CI, 48.5–83.2%) complete remission. Limited data on IVIG, cyclosporine, and plasmapheresis suggested partial efficacy in selected refractory cases. Conclusions: This meta-analysis may support clinical decision-making by clinicians. A stepwise approach is suggested: high-dose H₁ antihistamines as first-line therapy, phototherapy as an alternative option in patients with access to treatment centers, and omalizumab for those with insufficient response. In refractory cases, additional options might be considered.

Background: Vitiligo-like leucoderma is being increasingly reported in patients with breast cancer treated with cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors. Objectives: To systematically review the characteristics of CDK4/6 inhibitor-induced vitiligo-like leucoderma. Methods: A comprehensive literature search was conducted to identify published cases of patients with vitiligo-like leucoderma following CDK4/6 inhibitor therapy administered for advanced breast cancer. The cases of three additional patients from our tertiary vitiligo clinic are also reported. Results: Thirteen publications met the inclusion criteria, with a study population of 62 patients, including the 3 newly reported patients attending our vitiligo clinic. All patients were female; the median age was 61 years (range 39–87 years). Ribociclib was the CDK4/6 inhibitor most frequently associated with vitiligo-like leucoderma in 76% of patients (47/62). The condition predominantly affected sun-exposed areas (88%, 36/41) and caused symptoms such as intense pruritus in 59% of patients (24/41). Despite multiple treatment methods, 56% of the patients (34/61) showed no repigmentation. CDK4/6 inhibitor therapy was discontinued in 13 of 62 patients (21%) for various reasons, including vitiligo-like leucoderma; however, cessation did not improve the outcome. Most studies lacked data on progression-free survival. Conclusion: CDK4/6-inhibitor-induced vitiligo-like leucoderma has distinct clinical characteristics compared with classic vitiligo and is mostly recalcitrant to treatment. Stopping CDK4/6 inhibitors does not alleviate or improve the condition. Further research is essential to elucidate its prognostic significance.

Background: Vitiligo-like leucoderma is a rare cutaneous adverse event associated with cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors. However, its clinicopathological and immunohistochemical profiles remain unclear. Objectives: To characterize the clinical, pathological and immunohistochemical features of CDK4/6 inhibitor-induced vitiligo-like leucoderma. Methods: This retrospective case series describes five female patients with advanced or metastatic breast cancer who developed vitiligo-like leucoderma during CDK4/6 inhibitor therapy. Clinical data and skin biopsies were evaluated, including immunohistochemical analysis of melanocyte markers, cell-cycle protein (p16) and T-cell subsets. Results: The depigmented lesions appeared primarily in sun-exposed areas. Two patients exhibited an inflammatory phenotype with pruritus and a lichenoid rash. In all patients, the lesions progressed rapidly over several months and then stabilized. This course was maintained regardless of any vitiligo-targeted therapeutic interventions. Histopathological examination revealed complete absence of melanocytes in all biopsies. Three specimens (60%) had inflammatory changes, including lichenoid and perivascular lymphohistiocytic infiltrates, with immunohistochemistry showing a predominance of CD4+ T cells within the infiltrates. Features of chronic actinic damage (epidermal atrophy, orthokeratosis, reactive keratinocytes, dermal solar elastosis) were observed. In two biopsies (40%), there was a patchy distribution of p16 staining within basal and suprabasal keratinocytes. Four patients (80%) demonstrated prolonged (2–4 years) progression-free survival. Conclusions: CDK4/6 inhibitor-induced vitiligo-like leucoderma appears to be a distinct clinicopathological entity, characterized by a predictable course and stabilization, consistent inflammatory features, and a CD4-predominant immune profile. These findings suggest a unique pathogenic mechanism, either immune-mediated or associated with actinic damage, that distinguishes this condition from classic vitiligo and immune checkpoint inhibitor-induced vitiligo-like leucoderma.

Solid organ transplant recipients (SOTRs) have a significantly higher incidence of cutaneous squamous cell carcinoma (SCC), which often exhibit a more aggressive clinical course. Besides immunosuppression, a key risk factor for aggressive SCC is anatomical location—particularly tumors arising in the head and neck region. Recently, we observed an increasing number of SOTRs presenting with aggressive SCCs in the upper extremities—a site traditionally considered low risk. This study aimed to explore the clinical, pathological, and outcome features of these tumors. A retrospective search of the electronic files of a tertiary medical center was conducted (2016-2024) to identify SOTRs diagnosed with upper-extremity SCC with an aggressive course. Data on patient demographics, tumor characteristics, treatment, and outcomes were extracted. The cohort included 7 kidney transplant recipients who developed aggressive SCC in the upper extremities at a median of 31 years after transplantation. Treatments consisted of radical surgeries, radiotherapy, and chemotherapy. Six patients received immune checkpoint inhibitors, 3 of whom achieved a durable complete response. Two patients died of disease-related complications. Aggressive SCCs in the upper extremities are rare in SOTRs but may exhibit a highly malignant course. This series highlights the importance of heightened vigilance in SOTRs, particularly those with prolonged immunosuppression, even for SCCs arising in traditionally low-risk sites. The results also underscore the critical role of dedicated transplant dermatology clinics and the importance of multidisciplinary management in this complex population. Early identification and timely initiation of immunotherapy should be considered to improve outcomes.