Dermatology Case Discussion: Follicular Dermatoses and Diagnostic Differentials

Conclusions

• Dermatitis cruris pustulosa et atrophicans appears to be a chronic pruritic superficial folliculitis of the lower legs in young men from tropical settings that can progress from pustules to scaly, atrophic scarring alopecia.
• The condition is likely multifactorial, with Staphylococcus aureus, occlusion, trauma, and possibly heavy emollient use or traditional practices contributing to its development or persistence.
• Histopathology in dermatitis cruris pustulosa et atrophicans is often nonspecific but usually shows suppurative folliculitis and hyperkeratosis.
• The disease tends to be refractory to treatment, so management focuses on topical or systemic antibiotics when needed and, importantly, removing provoking factors.
• Follicular psoriasis is probably underrecognized and may present either alone or alongside classic plaque psoriasis, especially in females with dark skin.
• Follicular psoriasis can clinically mimic several other papular or follicular disorders, so it belongs in the differential for chronic scaly follicular eruptions.
• Its histology is not highly specific, but follicular plugging, shoulder parakeratosis, hypogranulosis, and perifollicular inflammation are supportive clues.
• A key takeaway is that shoulder parakeratosis should not automatically be attributed to seborrheic dermatitis, because PRP and follicular psoriasis are also important possibilities.