This study aimed to determine the prevalence of human epidermal growth factor receptor 2 (HER2)–ultralow breast cancer among cases initially classified as HER2 immunohistochemistry (IHC) 0 and assess interobserver variability in interpreting low-level HER2 expression. Methods: In this multicenter retrospective study, all invasive breast cancer cases diagnosed between January and December 2022 across 10 Korean institutions were retrieved. Institutional pathologists reexamined HER2 IHC slides originally reported as IHC 0 according to the 2018 American Society of Clinical Oncology/College of American Pathologists guidelines and reclassified them as HER2-null (0), HER2-ultralow (0+), or HER2-low (1+). Slides from 10% of HER2-null and HER2-ultralow cases were digitized for central review and independently assessed by two pathologists, with discrepancies resolved by consensus. Results: Among 8,026 cases, 2,836 cases (35.5%) were initially reported as IHC 0. Upon re-review, 1,673 (59.0%), 1,139 (40.2%), and 24 (0.8%) cases were reclassified as HER2-null, HER2-ultralow, and HER2-low, respectively. The prevalence of HER2-ultralow breast cancer varied considerably across institutions (23.7%–78.1%). Central review of 268 digitized cases showed concordance in 193 cases (72.0%). Among the 75 discordant cases, 54 tumors (72.0%) were upgraded from HER2-null to HER2-ultralow, and 18 (24.0%) tumors were upgraded from HER2-ultralow to HER2-low. Furthermore, two tumors (2.7%) were downgraded from HER2-ultralow to HER2-null. Conclusions: Approximately 40% of cases initially categorized as IHC 0 were reclassified as HER2-ultralow. The substantial inter-institutional variability observed in interpreting low-level HER2 expression highlights the need for standardized training and quality assurance to ensure accurate identification of patients eligible for HER2-targeted antibody–drug conjugates.

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a rare drug-induced skin reaction characterized by distinctive rashes. It presents as sharply demarcated erythema in “V” shape on the flexural areas such as the buttocks and the groin. Additionally, it can affect other flexural regions such as the axillae, popliteal fossae, and antecubital fossae. SDRIFE typically occurs within a few days following systemic drug exposure, without prior cutaneous sensitization. It is generally associated with a favorable prognosis with no systemic involvement. Consequently, treatment usually involves discontinuation of the offending drug and symptomatic management with antihistamines, with systemic corticosteroids rarely necessary. Herein, we report a case of severe SDRIFE that developed six weeks after denosumab administration and required long-term systemic corticosteroids.

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a rare drug-induced skin reaction characterized by distinctive rashes. It presents as sharply demarcated erythema in “V” shape on the flexural areas such as the buttocks and the groin. Additionally, it can affect other flexural regions such as the axillae, popliteal fossae, and antecubital fossae. SDRIFE typically occurs within a few days following systemic drug exposure, without prior cutaneous sensitization. It is generally associated with a favorable prognosis with no systemic involvement. Consequently, treatment usually involves discontinuation of the offending drug and symptomatic management with antihistamines, with systemic corticosteroids rarely necessary. Herein, we report a case of severe SDRIFE that developed six weeks after denosumab administration and required long-term systemic corticosteroids.

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a rare drug-induced skin reaction characterized by distinctive rashes. It presents as sharply demarcated erythema in “V” shape on the flexural areas such as the buttocks and the groin. Additionally, it can affect other flexural regions such as the axillae, popliteal fossae, and antecubital fossae. SDRIFE typically occurs within a few days following systemic drug exposure, without prior cutaneous sensitization. It is generally associated with a favorable prognosis with no systemic involvement. Consequently, treatment usually involves discontinuation of the offending drug and symptomatic management with antihistamines, with systemic corticosteroids rarely necessary. Herein, we report a case of severe SDRIFE that developed six weeks after denosumab administration and required long-term systemic corticosteroids.

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a rare drug-induced skin reaction characterized by distinctive rashes. It presents as sharply demarcated erythema in “V” shape on the flexural areas such as the buttocks and the groin. Additionally, it can affect other flexural regions such as the axillae, popliteal fossae, and antecubital fossae. SDRIFE typically occurs within a few days following systemic drug exposure, without prior cutaneous sensitization. It is generally associated with a favorable prognosis with no systemic involvement. Consequently, treatment usually involves discontinuation of the offending drug and symptomatic management with antihistamines, with systemic corticosteroids rarely necessary. Herein, we report a case of severe SDRIFE that developed six weeks after denosumab administration and required long-term systemic corticosteroids.

Heart failure (HF) is a major cause of mortality and morbidity in South Korea, imposing substantial physical, emotional, and financial burdens on patients and society. Despite the high burden of symptom and complex care needs of HF patients, palliative care and hospice services remain underutilized in South Korea due to cultural, institutional, and knowledge-related barriers. This position statement from the Korean Society of Heart Failure emphasizes the need for integrating palliative and hospice care into HF management to improve quality of life and support holistic care for patients and their families. By clarifying the role of palliative care in HF and proposing practical referral criteria, this position statement aims to bridge the gap between HF and palliative care services in South Korea, ultimately improving patient-centered outcomes and aligning treatment with the goals and values of HF patients.

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a rare drug-induced skin reaction characterized by distinctive rashes. It presents as sharply demarcated erythema in “V” shape on the flexural areas such as the buttocks and the groin. Additionally, it can affect other flexural regions such as the axillae, popliteal fossae, and antecubital fossae. SDRIFE typically occurs within a few days following systemic drug exposure, without prior cutaneous sensitization. It is generally associated with a favorable prognosis with no systemic involvement. Consequently, treatment usually involves discontinuation of the offending drug and symptomatic management with antihistamines, with systemic corticosteroids rarely necessary. Herein, we report a case of severe SDRIFE that developed six weeks after denosumab administration and required long-term systemic corticosteroids.

Background/Aims: The programmed death 1 (PD-1)/programmed death-ligand 1 (PD-L1) pathway has not been fully evaluated in inflammatory bowel disease. We evaluated PD-1/PD-L1 levels in patients with ulcerative colitis (UC) and their significance in tonsil-derived mesenchymal stem cells (TMSCs) treatment. Methods: Using acute and chronic murine colitis model, we measured the PD-1 and PD-L1 levels in inflamed colonic tissues pre- and post-treatment with TMSCs. We also measured PD-1 and PD-L1 levels in colonic tissues from UC patients, compared to normal controls. Results: In the analysis using human colonic tissues, a significant increase in the levels of PD-1 and PD-L1 was observed in the colonic mucosa of patients with UC compared with normal controls (p < 0.001 and p = 0.005, respectively). When comparing the maximal disease extent, PD-L1 levels were highest in patients with proctitis (38.5 ± 46.7), followed by left-side colitis (17.5 ± 23.1) and extensive colitis (5.2 ± 8.2) (p < 0.001). In the chronic colitis model, the level of PD-L1 was decreased (p = 0.040) and the level of PD-1 increased more than in normal controls (p = 0.047). After treatment with TMSC, significant improvements were observed in body weight, disease activity index, and colon length recovery. Additionally, the levels of PD-1 and PD-L1 were recovered; PD-L1 significantly increased (p = 0.031), while the level of PD-1 decreased (p = 0.310). Conclusions The altered expression of PD-1 and PD-L1 in colonic mucosa may be a possible mechanism of UC, and T-MSC-derived PD-L1 could help suppress colitis.

Allergen immunotherapy (AIT) has been used for over a century and has been demonstrated to be effective in treating patients with various allergic diseases. AIT allergens can be administered through various routes, including subcutaneous, sublingual, intralymphatic, oral, or epicutaneous routes. Sublingual immunotherapy (SLIT) has recently gained clinical interest, and it is considered an alternative treatment for allergic rhinitis (AR) and asthma. This review provides an overview of the current evidence-based studies that address the use of SLIT for treating AR, including (1) mechanisms of action, (2) appropriate patient selection for SLIT, (3) the current available SLIT products in Korea, and (4) updated information on its efficacy and safety. Finally, this guideline aims to provide the clinician with practical considerations for SLIT.

Allergen immunotherapy (AIT) is a causative treatment of allergic diseases in which allergen extracts are regularly administered in a gradually escalated doses, leading to immune tolerance and consequent alleviation of allergic diseases. The need for uniform practice guidelines in AIT is continuously growing as the number of potential candidates for AIT increases and new therapeutic approaches are tried. This updated version of the Korean Academy of Asthma Allergy and Clinical Immunology recommendations for AIT, published in 2010, proposes an expert opinion by specialists in allergy, pediatrics, and otorhinolaryngology. This guideline deals with the basic knowledge of AIT, including mechanisms, clinical efficacy, allergen standardization, important allergens in Korea, and special consideration in pediatrics. The article also covers the methodological aspects of AIT, including patient selection, allergen selection, schedule and doses, follow-up care, efficacy measurements, and management of adverse reactions. Although this guideline suggests the optimal dosing schedule, an individualized approach and modifications are recommended considering the situation for each patient and clinic.