**Core Concept**
Steroids are synthetic or naturally occurring hormones that influence various physiological processes. Topical steroids, in particular, are used to reduce inflammation in skin conditions. However, their prolonged use can lead to several side effects due to their vasoconstrictive and anti-inflammatory actions.

**Why the Correct Answer is Right**
Photosensitivity is not a known side effect of topical steroids. While steroids can cause skin atrophy, telangiectasia, and folliculitis, these are consequences of their vasoconstrictive and anti-inflammatory actions on the skin. Photosensitivity typically refers to an abnormal skin reaction to sunlight, often seen in conditions like porphyria or when taking certain medications like thiazides, sulfonamides, or certain antibiotics.

**Why Each Wrong Option is Incorrect**
**Option A:** Skin atrophy is a well-documented side effect of topical steroids, particularly with prolonged use. It occurs due to the reduction in collagen and elastin production, leading to thinning and loss of skin elasticity.

**Option B:** Telangiectasia, or dilated blood vessels, can also be a side effect of topical steroids. This is thought to be due to the vasoconstrictive action of steroids, which can cause blood vessels to become dilated and visible.

**Option C:** Folliculitis, an inflammation of hair follicles, can be caused by the use of topical steroids. This is often due to the disruption of the normal skin flora and the promotion of bacterial growth.

**Clinical Pearl / High-Yield Fact**
When using topical steroids, it's essential to use the lowest concentration for the shortest duration necessary to minimize the risk of side effects. Always weigh the benefits of treatment against the potential risks, and consider the patient's medical history and other potential contraindications.

**✓ Correct Answer: D. Photosensitivity. It is not a known side effect of topical steroids.**