This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy of Skin, Subject name: Skin
Treatment of choice of Nodulocystic Acne is : 
Select and explain. 
A. Erythromycin, B. Isoretinoin, C. Tetracycline, D. PUVA
B: Isoretinoin
Answer: B: Isoretinoin 
Explanation: Ans. is 'b' Isotretinoin [Ref Harrison 16/e, p 295 (Page 3151 Rexburg's 16/e Page 1561According to this table 3 choice are correct but Harrison says "that severe nodulocystic acne not responsive to oral antibiotics, hormonal therapy or topical therapy may be treated with synthetic retinoid, Isotretinoin."