## Core Concept
The patient's presentation of multiple, small hypopigmented macules on the upper chest and back, arranged around follicles, with fine scaling on the surface, is suggestive of a superficial fungal infection. The condition described is likely **pityriasis versicolor**, also known as **tinea versicolor**.

## Why the Correct Answer is Right
The description provided matches the clinical features of pityriasis versicolor, which is caused by the yeast **Malassezia**. This condition is characterized by hypopigmented or hyperpigmented macules, typically on the chest and back, with fine scaling. The yeast lives on the skin and can cause disease under certain conditions. The arrangement of lesions around follicles and their tendency to coalesce are classic features. The diagnosis can be confirmed by **potassium hydroxide (KOH) examination** of skin scrapings, which would reveal the characteristic **spaghetti and meatballs** appearance of hyphae and yeast cells.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is not provided, but typically, incorrect options might include investigations not directly related to fungal infections, such as blood tests for autoimmune conditions or bacterial cultures.
- **Option B:** This option is also not provided, but similarly, it might include other types of diagnostic tests not specific for fungal infections, like imaging studies.
- **Option C:** Without the specific details of Option C, it's difficult to address directly, but if it were an option like PCR for a bacterial infection, it would be incorrect because pityriasis versicolor is caused by a yeast.
- **Option D:** Similarly, without specifics, if Option D suggested a test not relevant to diagnosing superficial fungal infections, it would be incorrect.

## Clinical Pearl / High-Yield Fact
A key clinical pearl for diagnosing pityriasis versicolor is the **scraping and KOH preparation**. When skin scrapings are treated with KOH and viewed under a microscope, the presence of both **hyphae (spaghetti)** and **yeast cells (meatballs)** confirms the diagnosis. This condition often recurs, which aligns with the patient's history of similar lesions one year ago.

## Correct Answer Line
**Correct Answer: B. Skin scrapings for KOH examination.**