An Unexpected Cutaneous Response to a Skin Test to Paclitaxel: A Case Report

Taxanes are a group of antineoplastic agents widely used in the treatment of various cancers, including breast cancer, due to their mitotic inhibitory effects. Hypersensitivity reactions (HRs) to paclitaxel typically occur immediately, often within the first few minutes of infusion during the initial chemotherapy cycle.

A 75-year-old woman was diagnosed with grade 1-2 invasive ductal breast carcinoma at stage T2N1M1. During her first chemotherapy cycle, starting the infusion of paclitaxel, the patient experienced facial flushing, dyspnea (SatO2 92%), and dizziness with hypotension. A 0.6 mg/mL intradermal test concentration yielded a positive result, characterized by a 10-mm blister with exudation. A punch biopsy showed a subepidermal blister with partial epidermal necrosis. Intravascular occlusion was also described, with thrombi present in small vessels within the dermis. No coagulation alterations were detected after a complete workup.

Desensitization to paclitaxel was dismissed for caution, as there was a high risk of severe delayed drug reaction. Desensitization to docetaxel with premedication was scheduled for patient safety in order to continue taxane-based treatment. Despite docetaxel desensitization, the patient presented a progressive, severe dermatitis on the hands. After six cycles, docetaxel was finally suspended because of this severe dermatitis. She continued receiving pertuzumab and trastuzumab, and she started on hormone therapy with letrozole.

We present a case of an immediate reaction during paclitaxel infusion, as indicated by a positive immediate-reading intradermal test, suggestive of a T-cell-mediated delayed-type hypersensitivity reaction. Desensitization to paclitaxel was avoided out of caution. Desensitization to docetaxel with premedication was planned following negative skin tests (STs); however, the development of severe hand dermatitis necessitated discontinuation of taxanes due to suspected cross-reactivity. We hypothesize that the patient exhibited a “converter phenotype,” transitioning from an initial immediate drug hypersensitivity reaction (IDHR) to a non-immediate drug hypersensitivity reaction (NIDHR) upon docetaxel exposure. In this case, the intradermal test with paclitaxel may have served as a predictive marker for this phenomenon.