Toxin-Induced Nodules: A Clinically Distinct Complication With Implications for Aesthetic Practice.

[BACKGROUND] Botulinum toxin type A is widely used for aesthetic purposes and is generally considered safe. However, rare complications such as nodule formation at injection sites can occur, posing diagnostic and therapeutic challenges.

[AIMS] To describe a case report of patients developing inflammatory nodules after incobotulinum toxin A injections, review the differential diagnoses, and discuss appropriate management strategies based on clinical outcomes and literature.

[PATIENTS/METHODS] We report three cases of healthy female patients (ages 35-40) who presented with localized nodules approximately 1 cm in diameter following a full-face treatment with Inco botulinum toxin A for treatment of rhytides. Nodules appeared at the frontal injection sites immediately after treatment and were evaluated through clinical examination and ultrasound imaging. Only one patient received empirical anti-inflammatory and antibiotic therapy; the others were managed conservatively with observation alone.

[DISCUSSION] All cases resolved spontaneously in one and 2 months, with no scarring or pigmentation changes. Although histopathological confirmation was not performed, the benign clinical course and absence of systemic symptoms suggest a transient inflammatory or hypersensitivity reaction rather than infectious or granulomatous pathology. Literature review supports a multifactorial aetiology, including immune-mediated, foreign-body, and rare infectious causes. Early identification and conservative management are often sufficient, though persistent or atypical cases may warrant biopsy and targeted therapy.

[CONCLUSIONS] Nodule formation following incobotulinum toxin A injection is an uncommon but important clinical entity. Awareness of its presentation and natural course can prevent unnecessary interventions. Further research is needed to define diagnostic algorithms and management guidelines.