Stevens-Johnson syndrome is an autoimmune condition characterised by erythematous target lesions on the skin with involvement of the oral and genital mucosa and conjunctivae. Recent case reports describe incomplete presentations with absence of the characteristic skin changes. This is caused by extrapulmonary manifestations of Mycoplasma pneumoniae lung infection and is now recognised as M. pneumoniae-associated mucositis (MPAM). This case report describes the clinical presentation of MPAM in a 17-year-old girl and highlights the importance of the recognition and the appropriate clinical management.