Abemacilib‐Related Radiation Recall Dermatitis Post Breast Reconstruction: A Case Report and Literature Review

ABSTRACT

Radiation recall dermatitis (RRD) is an inflammatory skin reaction confined to areas previously exposed to radiation, triggered by subsequent systemic therapy. This case report describes a female patient with hormone receptor‐positive, human epidermal growth factor receptor 2‐negative breast cancer. She received 6 cycles of neoadjuvant chemotherapy, followed by mastectomy with immediate tissue expander implantation and axillary lymph node dissection. Adjuvant radiotherapy and intensive endocrine therapy (endocrine therapy and abemaciclib) were administered postoperatively. After radiotherapy, the patient developed small, coin‐sized skin flap necrosis. Two months after completing radiotherapy, she initiated abemaciclib treatment, which was followed by rapid progression of flap necrosis and increased exposure of the tissue expander. This flap necrosis was suggestive of RRD. This report details the clinical course, management strategies, and a review of relevant literature, aiming to provide valuable insights for clinicians in handling similar cases and enhance awareness of potential risks associated with this treatment combination.

Radiation recall dermatitis (RRD)—an inflammatory reaction in previously irradiated skin triggered by subsequent systemic therapy. This report presents a case of a breast cancer patient who developed injection port exposure following radiotherapy after breast reconstruction; subsequent oral administration of abemaciclib led to the occurrence and rapid progression of skin necrosis. This suggests that caution should be exercised regarding the occurrence of RRD when administering CDK4/6i following radiotherapy.

1. Introduction

Radiation recall dermatitis (RRD), first reported in 1959 in association with actinomycin‐D [1], refers to inflammatory reactions in previously irradiated skin triggered by subsequent systemic therapy. It has since been linked to agents including docetaxel, gemcitabine, trastuzumab, pembrolizumab, and even COVID‐19 vaccines [2, 3, 4], though most evidence remains limited to case reports due to the lack of large‐scale clinical studies.

Radiotherapy is a cornerstone of adjuvant breast cancer treatment but impairs tissue repair and increases dermatological complications. Abemaciclib, a cyclin‐dependent kinase 4/6 inhibitor (CDK4/6i), significantly improves 5‐year invasive disease‐free survival (IDFS) and distant relapse‐free survival (DRFS) by 7.6% and 6.7%, respectively, when combined with endocrine therapy for luminal breast cancer [5]. However, its association with RRD remains poorly characterized, particularly in breast reconstruction patients—where literature on abemaciclib‐radiotherapy interactions affecting flap healing and dermatitis development is extremely scarce.

This report details the clinical course of abemaciclib‐induced RRD in a post‐radiotherapy breast reconstruction patient, supplemented by literature review, to improve understanding of this underrecognized complication and guide clinical decision‐making.

2. Case Report

A 41‐year‐old premenopausal woman was diagnosed with stage IIB (cT2N1M0) right breast invasive ductal carcinoma in March 2024. Core needle biopsy and immunohistochemistry revealed estrogen receptor positivity (90%), progesterone receptor positivity (> 90%), and human epidermal growth factor receptor 2 negativity (1+). Breast ultrasound confirmed multicentric lesions, and axillary lymph node puncture showed metastasis. She completed 6 cycles of neoadjuvant TEC chemotherapy after informed consent.

Due to multicentric lesions, breast‐conserving surgery was not feasible, but the patient desired breast preservation. After comprehensive evaluation (including postoperative radiotherapy planning), she underwent subcutaneous total mastectomy (nipple‐areolar complex resection), immediate prepectoral tissue expander (420 mL saline) and TiLoop patch implantation, plus axillary lymph node dissection.

Postoperative pathology showed Miller‐Payne grade I, 12/14 lymph node metastasis, and pathological stage ypT2N3M0. Half a month post‐surgery, she started endocrine therapy: subcutaneous goserelin (3.6 mg every 28 days) plus aromatase inhibitors (AIs).

From November 27 to December 31, 2024, she received adjuvant radiotherapy (right chest wall, regional lymph nodes, supraclavicular fossa; 50Gy total dose in 25 fractions of 2Gy each). Five days post‐radiotherapy, she developed needle‐prick pain at the expander injection port; 1 month later, the port was fully exposed. Regular dressing changes and anti‐inflammatory treatment stabilized the incision without deterioration.

On March 14, 2025, adjuvant abemaciclib (150 mg twice daily) was initiated. One week later, the original incision dehisced and rapidly expanded to 10 × 10 cm², with visible expander and patch exposure. According to RTOG (Radiation Therapy Oncology Group) grade, the patient of radiation‐induced skin injury is Grade IV, which is characterized by the presence of skin ulcers, bleeding, and necrosis. On April 23, 2025, she was hospitalized for expander/patch removal and debridement suture, with good postoperative flap healing (Figure 1).

FIGURE 1.

Photos taken after the patient received radiotherapy and was administered abemaciclib. (A) Day 5 of RT (radiotherapy). (B) 9 days after radiotherapy, the water injection valve became completely exposed. (C–I) 2 weeks after oral administration of abemaciclib, the original incision dehisced, and the defect increased rapidly from March 31, 2025 to April 8, 2025. (J) The patient was hospitalized on April 23, 2025, and underwent removal of the expander and patch plus debridement and suture. (K) The flap healed well about one month after the surgery.

The patient had no history of diabetes, smoking, or other systemic diseases. Laboratory tests (complete blood count (CBC), liver/kidney function, coagulation profiles) were within normal ranges. The patient's entire treatment process is summarized in Figure 2.

FIGURE 2.

The treatline of the patient.

3. Discussion

The patient's complications likely resulted from synergistic effects of abemaciclib and radiotherapy on tissue repair. Radiotherapy reduces breast cancer recurrence [6] but causes skin/vascular injury and fibrosis, increasing reconstruction‐related complications (hematoma, seroma, infection, wound dehiscence, capsular contracture) [7]. While this patient developed post‐radiotherapy skin issues, flap necrosis remained stable for 2 months—until abemaciclib initiation triggered rapid deterioration. The temporal correlation strongly suggests abemaciclib‐induced RRD. We also considered infection as a cause of the patient's poor incision healing and flap necrosis. However, the patient had no fever, normal CBC results, and no obvious purulent discharge at the wound site when incision dehiscence and condition progressed rapidly. Additionally, after discontinuing abemaciclib and surgically removing the tissue expander, the flap healed well. Thus, infection was basically ruled out. Abemaciclib was started 2 months post‐radiotherapy, ruling out radiosensitization (typically associated with concurrent or < 7‐day interval between radiotherapy and drug administration) [8]. RRD typically occurs months to years after radiotherapy, Jamaluddin et al. [9] even reported recurrent RRD 40 years post‐breast cancer radiotherapy. Literature on CDK4/6i‐induced RRD is scarce: only Yi et al. [10] reported two abemaciclib‐induced RRD cases, and Erjan et al. [11] documented one ribociclib‐induced case (Table 1).

TABLE 1.

Clinical case characterization of CDK4/6i induced RRD.

Authors	Year of publication	Surgical technique	Triggering cdk4/6i	Timing of drug administration	RT dose (Gy)/fraction	RT time	RRD grade	Drug‐RRD time	Outcome
Yi et al. [10]	2025	Mastectomy followed by the tissue expander placement	Abemaciclib	1 month after surgery	50/25	1 month after surgery	3	4 months	Take out the expander and resumed abemaciclib after 2 months of surgery
		Mastectomy followed by the tissue expander placement	Abemaciclib	5 months before surgery	50/25	1 month after surgery	3	34 days	Take out the expander and undergone TRAM and resumed abemaciclib 5 months of surgery
Erjan et al. [11]	2020	Bilateral modified radical mastectomy	Ribociclib		37.5/5		2	10 days	Topical steroids and hyaluronic acid managed RRD successfully

Abbreviations: CDK4/6i = a cyclin‐dependent kinase 4/6 inhibitor; RRD = radiation recall dermatitis; RT = radiotherapy; TRAM = transverse rectus abdominis musculocutaneous.

Abemaciclib inhibits Rb phosphorylation, blocking G1‐to‐S phase cell cycle progression and inducing senescence/apoptosis [12]. Wound healing requires coordinated action of platelets, keratinocytes, fibroblasts, macrophages, and endothelial cells [13]; abemaciclib may impair proliferation of these cells, as CDK4/6i are known to interfere with immune sentinel cell maturation [14]. Silvestri et al. [15] reported 13 CDK4/6i‐induced dermatologic reactions, including RRD. Notably, abemaciclib's package insert [16] lists side effects (diarrhea, nausea, infections, etc.) but not flap healing impairment or RRD risk. We considered whether the dermatitis was linked to the patient's drug allergy. Abemaciclib's common skin‐related adverse reactions (e.g., rash, pruritus) are mostly generalized, dose‐related, and rapidly relieved after drug withdrawal [16]. However, the patient's skin lesions were confined to the post‐breast‐reconstruction radiotherapy area, not generalized or non‐specific. Thus, this is inconsistent with a drug allergy.

We also evaluated reconstruction methods: the patient underwent two‐stage prepectoral breast reconstruction (PPBR), which offers excellent aesthetics and stability [17]. Post‐mastectomy radiotherapy (PMRT) is associated with lower capsular contracture rates in PPBR (16.1%) than subpectoral reconstruction (52.2%, p = 0.0018) [18], though infection/seroma rates are similar [19]. Thus, subpectoral reconstruction would not have reduced RRD risk.

Autologous reconstruction (rectus abdominis/latissimus dorsi flaps) has superior safety in post‐radiotherapy settings due to native vascular supply, but carries longer operative/recovery times and donor‐site risks [20]. Literature on CDK4/6i‐induced RRD in autologous reconstruction is lacking; the patient declined this option during initial planning.

With the growing use of CDK4/6i and breast reconstruction, clinicians must vigilantly monitor radiotherapy‐drug interactions. Unanswered questions include: optimal timing (pre/during/post‐radiotherapy) and dosage of CDK4/6i; duration of delay for high‐risk patients; and reconstruction method selection for patients requiring radiotherapy and CDK4/6i. This case highlights the need for tailored treatment plans to mitigate RRD risk.

Author Contributions

Conceptualization: Xinzhong Chang. Writing – original draft: Zhaobo Jia and Lijin Gao. Writing – review and editing: Xinzhong Chang, Zhaobo Jia, and Lijin Gao. Resources and supervision: Xiaochuan Tang and Lijin Gao.

Funding

The authors have nothing to report.

Conflicts of Interest

The authors declare no conflicts of interest.

Jia Z., Gao L., Tang X., and Chang X., “Abemacilib‐Related Radiation Recall Dermatitis Post Breast Reconstruction: A Case Report and Literature Review,” Thoracic Cancer 17, no. 3 (2026): e70217, 10.1111/1759-7714.70217.

Data Availability Statement

In accordance with the ICMJE data sharing policy, the authors have agreed to make the data available upon request.