Unilateral axillary adenopathy may be caused by a wide range of both benign and malignant aetiologies. While the most common cause is inflammation, infection or trauma of the breast, thoracic wall or arm, a significant proportion of cases are due to occult malignancy. In female patients particularly, breast malignancy must be excluded with mammography and ultrasound. Local inflammation, infection or trauma of the thoracic wall or arm should also be sought when deciding the most appropriate recommendation for management. This case report outlines the most significant pathologies and discusses the need to rule out sinister pathology, even when a benign local cause is evident.