Subcutaneous nodules following vaccination

Five patients presented to surgical clinics at our institution with subcutaneous nodules of the upper arm or thigh present for 6-18 months. Excisional or fine-needle biopsy was performed due to diagnostic uncertainty and parental concern. Histopathological examination revealed these to be cutaneous lymphoid hyperplasia in reaction to vaccine components. Nodular reactions with this histopathological pattern are well recognised within vaccine-related literature, but less commonly recognised in patients presenting to general paediatric or surgical clinics. This article reviews literature on delayed-onset nodule formation after vaccination and recommends observation and reassurance as mainstays of management of this largely benign entity.