What is the rare but well-documented cause of this recurrent chest infection?

Abstract

A 61-year-old female presented with a history of recurrent chest infections over several years. Episodes were characterised by cough and green sputum without haemoptysis. There was no history of chest pain, shortness of breath, fever, night sweats or weight loss. She had received several courses of antibiotics for this from her general practitioner. Her past medical history included whooping cough as a child and hysterectomy at age 40 years, for reasons unknown. She had smoked 10 cigarettes per week since her teenage years and denied any alcohol intake. There were no pets at home or any history of recent travel.

An unusual case of recurrent pneumonia

“…Recurrent chest infections are considered especially suspicious as they may indicate underlying lung cancer24 or immunodeficiency 25…”