**Core Concept**
The patient's presentation of acne with nodules, cysts, and intercommunicating sinuses suggests a diagnosis of severe acne, also known as acne conglobata. This condition is characterized by large, painful nodules and abscesses that can lead to scarring and disfigurement if left untreated.

**Why the Correct Answer is Right**
The treatment of choice for severe acne is a systemic antibiotic, specifically isotretinoin. Isotretinoin works by reducing the production of sebum, which is the oily substance produced by the sebaceous glands that can clog pores and lead to acne. It also has anti-inflammatory properties, which can help to reduce the size and number of nodules and cysts. Additionally, isotretinoin can help to prevent scarring by reducing the amount of inflammation and promoting the healing of damaged skin.

**Why Each Wrong Option is Incorrect**
* **Option A:** Topical retinoids, such as adapalene or tretinoin, are commonly used to treat mild to moderate acne, but they are not effective for severe acne with nodules and cysts.
* **Option B:** Oral antibiotics, such as doxycycline or minocycline, can be used to treat moderate to severe acne, but they may not be sufficient to control the symptoms of severe acne.
* **Option D:** Hormonal therapy, such as spironolactone, may be used to treat acne in women with polycystic ovary syndrome (PCOS), but it is not the treatment of choice for severe acne.

**Clinical Pearl / High-Yield Fact**
It's essential to note that isotretinoin can have significant side effects, including increased risk of depression, anxiety, and birth defects, so it should only be used under the close supervision of a dermatologist.

**Correct Answer:** C. Isotretinoin.