Question

A child has a wart on her thumb for a few days and decides to get a check up. Just seven days before the same child had sores around her mouth and a runny nose, which eventually went away. Her guardian brings her in for examination. Head and neck exam are normal. Proximal to the back of her fingernail on her left thumb is a lesion. It appears as a cluster of small vesicles with a faint area of surrounding erythema. The remainder of the exam is normal. Given that she is diagnosed with Herpetic Whitlow due to Herpes Simplex 1, answer #2-7

Answer 1

1. Differential diagnosis :

1. Infectious tenosynovitis : it has the same clinical picture as above. The culture of suppurative synovial fluid is done. The culture should detect the presence of bacteria like gonococcal or mycobacterium or other aerobic or anaerobic bacteria. If the bacteria is absent it eliminates possibility of tenosynovitis

2. Kaposi’s sarcoma : HIV associated kaposi sarcoma is caused due to human herpes virus 8. It can be diagnosed through biopsy of tumour cell. Absence of herpes virus 8 eliminates its possibility.

3. Paronychia : it is caused by bacteria, yeast or fungi. Absence of these microbrs eliminates the disease possibility.

2. Herpetic Whitlow affects the distal phalanx. It affects nail bed and the cuticle. It is caused by herpes simplex virus attack through exposure to infected body fluids via a discontinuity in the skin, mostly a damaged cuticle. The virus invades the cells of the dermis and subcutaneous tissue.

3. Diagnosis is made through clinical finding. Laboratory tests include :

• Tzanck test
• viral cultures
• serum antibody titters
• fluorescent antibody testing
• DNA hybridization

4. Epidemiology : it affects all age groups. It is more common in children who have habit of taking their hands in mouth. It is also common in healthcare workers who gets affected with infected fluids from patients. Its incidence has been reported at 2.4 cases per 100,000 people per year.