Acrodermatitis continua of Hallopeau (ACH) is a rare, localized variant of pustular psoriasis characterized by painful paronychia. It primarily affects the distal phalanges and is frequently refractory to standard topical treatments. Establishing an optimal systemic therapy is clinically challenging, particularly for women of childbearing age, given the teratogenicity of retinoids and methotrexate, as well as the adverse effect profiles associated with cyclosporine. Herein, we present two cases of Japanese women in their 30s with recalcitrant ACH who were treated with apremilast. In Case 1, erythema and pain resolved within two months. In Case 2, while skin lesions responded favorably, persistent joint symptoms and headaches necessitated a switch to risankizumab. To evaluate broader utility, we analyzed 10 ACH cases (our two and eight from literature). Clinical efficacy for skin lesions was observed in 90% (9/10), and the response rate for joint pain reached 80% (4/5), with a median response time of 2 months. Notably, apremilast also demonstrated a favorable safety profile even with comorbidities like viral hepatitis. Although 30% of patients experienced mild adverse events (e.g., nausea, headache), the medication was generally well-tolerated. While this review is limited by potential publication bias inherent to case reports, and treatment responses vary, with one study showing limited efficacy, apremilast may be considered among systemic treatment options. Given its non-teratogenic nature and cost-effectiveness compared to biologics, we recommend apremilast as one of the first-line systemic treatment options for ACH patients resistant to topical regimens, especially those of childbearing potential.

Erdafitinib is a fibroblast growth factor receptor 1-4 inhibitor used for locally advanced or metastatic urothelial carcinoma in patients who have experienced disease progression after at least 1 prior systemic therapy. Various cutaneous side effects of erdafitinib have been reported, most commonly stomatitis and nail changes such as onycholysis, nail dystrophy, and paronychia. However, onychomadesis is a rarer nail toxicity that can cause significant discomfort and may necessitate treatment interruption. We present the case of a 61-year-old White man with metastatic urothelial carcinoma treated with 8 mg of erdafitinib daily who developed diffuse onychomadesis within a few months of initiating therapy. Awareness of the potential cutaneous side effects of erdafitinib and timely referral for specialty dermatologic care are important to allow treatment continuation.

IntroductionOsimertinib is a common treatment for epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC). EGFR inhibitors, such as osimertinib, are known to cause cutaneous toxicities including acneiform rash, paronychia, dry skin, and rarely urticaria. For patients with severe reactions that need osimertinib rechallenge, they can undergo a complex desensitization with serial drug dilutions.Case reportWe describe a case of osimertinib-related severe urticaria in a 47-year-old male with EGFR-mutated NSCLC. Ten days after initiation of osimertinib, the patient developed diffuse urticaria that was refractory to systemic corticosteroids. He was subsequently switched to erlotinib, which was discontinued due to a severe acneiform rash. It was decided to rechallenge with osimertinib.Management and OutcomeOsimertinib rechallenged using intensive urticaria prophylaxis with a regimen of loratadine, famotidine, and montelukast. The patient was slowly titrated off each agent and at the time of this report, the patient continues with loratadine twice daily and has remained on osimertinib for more than three years without recurrence of urticaria.DiscussionAlthough cutaneous toxicities are well described with osimertinib, management of severe urticaria utilizes complex desensitization or drug discontinuation. This case may represent a more pragmatic approach to osimertinib rechallenge that may be implemented for select patients.

Dacomitinib, a second-generation, irreversible epidermal growth factor receptor tyrosine kinase inhibitor that was approved for the treatment of non-small cell lung cancer in 2018, has limited real-world safety data. This study investigates dacomitinib-associated adverse events (AEs) using the United States Food and Drug Administration Adverse Event Reporting System (FAERS) database. We conducted a retrospective analysis of the FAERS database, extracting dacomitinib-related reports from 2018 Q3 to 2024 Q3. To assess the association between dacomitinib and AEs, we employed multiple disproportionality analyses, including the reporting odds ratio (ROR), proportional reporting ratio, Bayesian confidence propagation neural network, and multi-item gamma Poisson shrinker. From the FAERS database, we analyzed 10,869,881 case reports, identifying 594 dacomitinib-related AEs. Among these, 56 significant PTs were retained based on the four algorithms. Common AEs included diarrhoea (ROR 4.40), rash (ROR 6.40), paronychia (ROR 347.91), mouth ulcers (ROR 32.24), dermatitis acneiform (ROR 58.79), palmar-plantar erythrodysaesthesia (ROR 16.08), liver injury (ROR 5.56), and pulmonary fibrosis (ROR 9.75), aligning with the drug label. In addition, some unanticipated major AEs were detected, including cholestasis (ROR 6.12), cholelithiasis (ROR 6.56), an increase in blood pressure (ROR 6.85), an elevation in heart rate (ROR 4.91), a decline in red blood cell count (ROR 5.95), a decrease in hemoglobin (ROR 5.95), the presence of pericardial effusion (ROR 5.59), white matter lesions (ROR 98.11), and cerebral atrophy (ROR 56.69). All reported RORs for the identified AEs were statistically significant, as defined by a lower limit of the 95% confidence interval that exceeded 1. This study systematically evaluates AEs associated with dacomitinib, confirming its known safety profiles and identifying some emerging safety concerns in real-world settings. These findings provide crucial insights for clinicians and pharmacists to better manage dacomitinib's safety profile.

Amivantamab, an epidermal growth factor receptor (EGFR)-MET bispecific antibody, has demonstrated clinically meaningful benefits for patients with EGFR-mutated advanced non-small cell lung cancer (NSCLC). Consistent with EGFR and MET inhibition, amivantamab-containing regimens are associated with adverse events (AEs) including dermatologic AEs, edema, hypoalbuminemia, venous thromboembolism (VTE), and infusion-related reactions (IRRs). Here we provide practical consensus guidelines developed by a steering committee of 12 clinicians and supported by a literature review of current clinical recommendations, in addition to interviews with representatives of 2 patient advocacy groups, on managing the safety profile of amivantamab-containing regimens for clinicians in the Asia-Pacific (APAC) region. Consensus clinical guidelines recommend prophylactic anticoagulants, minocycline/doxycycline, and moisturizers as key management of common AEs associated with amivantamab, with detailed guidance provided for reactive management across AE grades. Guidance was based on published supportive care strategies for amivantamab and previous evidence on managing EGFR and MET tyrosine kinase inhibitor-related AEs. Prophylactic strategies and reactive treatments were summarized for skin-related AEs, paronychia, mucositis, and stomatitis. Recommendations for preventing and treating MET-related AEs, VTEs, and IRRs were also provided. Multidisciplinary team involvement in early intervention and management of AEs was encouraged. Patient advocacy groups advised clinicians to clearly explain the rationale for prophylactic and reactive treatments and to educate patients on how to appropriately and most efficiently utilize daily supportive care. Appropriate strategies based on these guidelines are encouraged and achievable for APAC clinicians to improve patient care during treatment with amivantamab-containing regimens.

Retronychia should be suspected in patients presenting with painful proximal nail fold inflammation of the great toe, particularly when nail growth has slowed or ceased. Early recognition prevents misdiagnosis as paronychia or onychomycosis. Complete nail plate avulsion remains the most effective treatment for symptom resolution.

MEK inhibitors (MEKi) have transformed the treatment of tumors such as melanoma and plexiform neurofibroma in neurofibromatosis type 1, but they are frequently associated with dermatological adverse effects that may affect quality of life and treatment adherence. This expert consensus reviews the evidence and provides practical recommendations for the prevention and management of the most common cutaneous toxicities associated with MEKi, including acneiform rash, eczematous dermatitis, xerosis, paronychia, photosensitivity, hair disorders, pruritus, edema, and mucositis. Most of these reactions are mild or moderate and can be controlled through preventive measures, topical or oral treatment, and patient education. Multidisciplinary collaboration between dermatology and oncology is key for early detection, individualized management, and optimization of clinical outcomes, minimizing treatment interruptions and improving the quality of life of patients receiving these therapies.