Scabies

Diagnosis: Scabies

Scabies

Clinical Presentation

Scabies

Clinical History

Submitted by dermRounds Dermatology Network. Originally posted January 2, 2017.

Treatment

See case discussion.

Differential Diagnosis

• Atopic dermatitis • Contact dermatitis • Insect bites • Dermatitis herpetiformis • Prurigo nodularis • Bullous pemphigoid • Drug eruption

Key Learnings

• Caused by Sarcoptes scabiei var. hominis — obligate human parasite • Pruritus is an allergic reaction to mite proteins — may take 2-6 weeks to develop in first infection • Pathognomonic finding: burrow (S-shaped or linear tunnel) in web spaces, wrists, elbows • Crusted (Norwegian) scabies: massive mite burden in immunocompromised — highly contagious • Treat all household contacts simultaneously even if asymptomatic • Post-treatment pruritus may persist for 2-4 weeks — does not indicate treatment failure • Dermoscopy: "delta wing" or "hang glider" sign (triangular, brown structure = mite head) • Nodular scabies: persistent pruritic nodules (hypersensitivity reaction) may persist for months after treatment

Tags: scabies, dermrounds dermatology network