Understanding Scarring Alopecia

Scarring (cicatricial) alopecia refers to permanent hair loss that occurs when hair follicles are destroyed and replaced by fibrous scar tissue, so regrowth is not possible. This is distinct from non-scarring alopecia, where the follicle is preserved and hair regrowth can occur once the underlying cause resolves.

Evaluating Each Option

• Androgenic Alopecia: This is the common male/female pattern baldness caused by progressive miniaturization of hair follicles under androgenic influence. The follicles remain structurally intact, so this is a non-scarring alopecia.
• Radiotherapy: Ionizing radiation to the scalp damages the follicular stem cells and, depending on dose, causes fibrosis and permanent destruction of hair follicles, replacing them with scar tissue. High-dose radiotherapy is therefore a well-recognized cause of permanent, scarring alopecia, making this the correct answer.
• Syphilis: Secondary syphilis classically produces a patchy, "moth-eaten" alopecia of the scalp. This hair loss is temporary and follicles are not destroyed, so it resolves completely with antibiotic treatment — it is a non-scarring alopecia.
• Alopecia Areata: An autoimmune, T-cell mediated attack on hair follicles causing patchy hair loss. The follicular architecture is preserved (it goes into a resting phase rather than being destroyed), so hair typically regrows either spontaneously or with treatment. It is the prototype of non-scarring alopecia.

Conclusion

Among the given options, only Radiotherapy (Option B) causes true follicular destruction with fibrous replacement, making it the correct cause of scarring alopecia. Androgenic alopecia, syphilis, and alopecia areata are all classic examples of non-scarring alopecia where the hair follicle is preserved and regrowth remains possible.