Herpes zoster is a disease caused by reactivation of varicella zoster virus, presenting with a prodrome of severe pain and fever followed by a typical cutaneous vesicular eruption in a dermatomal distribution. Herpes zoster rarely involves the mandibular division of the trigeminal nerve. This case highlights an unusual presentation of herpes zoster mandibularis in an immunocompromised patient with previous head and neck surgery, with relative sparing of the cheek. Previous parotid surgery led to an atypical anatomical pattern of herpes zoster reactivation. Sparing of regions within the dermatome may occur due to damage to sensory fibres innervating the skin during surgery as the axonal transport mechanisms are likely disrupted. Previous surgery can make diagnosis difficult by affecting the pattern of varicella zoster virus presentation, leading to uncharacteristic clinical features. This case demonstrates the importance of critically considering past medical and surgical history in clinical diagnosis and management of the disease.