[2] He studied medicine at St Thomas' Hospital, and after qualifying with a MB BChir in 1942 and graduating with an MD in 1950 with a thesis on keratoacanthoma and blistering eruptions,[1][2] did three years National Service[3] with the Royal Air Force, achieving the rank of squadron leader.

At the age of 32, he became a consultant dermatologist at Cardiff[2] and in 1953 moved to Addenbrooke's Hospital, Cambridge, where he spent many years.

[7] Described as a "crateriform ulcer of the face"[8] by Sir Jonathan Hutchinson in 1889,[8] it was then named "molluscum sebaceum" in 1936 by MacCormac and Scarf,[9] before the term keratoacanthoma was coined by histopathologist Walter Freudenthal[10][11] and then first formally used by Rook and the pathologist Ian Whimster in 1950.

[8] They noted that the condition lacked much attention despite being so common[10] and indicated that despite the suggestion that keratoacanthoma was histologically malignant, they believed the lesion was clinically benign.

[13] In 1979, Rook and Whimster revised their work and mentioned that squamous cell carcinoma could develop in a keratoacanthoma.

[15] Rook was known for the ability to read in six languages and he absorbed the latest dermatological scholarship from around the world which he could quote with authority.