Random Dermatology MCQ - Dyskeratosis Congenita

A 2-year-old boy presents with coarse, sparse hair, dystrophic nails, and reticulated hyperpigmentation on his neck and chest. His mother reports he has had frequent oral ulcerations and epistaxis. A bone marrow biopsy shows hypocellularity. Which of the following is the most likely diagnosis?

A) Dyskeratosis congenita
B) Epidermolysis bullosa
C) Netherton syndrome
D) Pachyonychia congenita
E) Kindler syndrome

Correct Answer: A) Dyskeratosis congenita

Explanation

This patient has dyskeratosis congenita (DC), a telomere biology disorder characterized by the classic triad:

1. Reticulated skin pigmentation (neck/chest)

2. Nail dystrophy (thin, ridged nails)

3. Oral leukoplakia (premalignant)

Additional key features:

• Bone marrow failure (pancytopenia, hypocellular marrow)

• Premature aging (early graying, pulmonary fibrosis)

• High cancer risk (SCC, AML)

Why not the others?

• (B) Epidermolysis bullosa: Blistering after trauma, no pigmentation/nail changes

• (C) Netherton syndrome: Bamboo hair (trichorrhexis invaginata), ichthyosis, atopy

• (D) Pachyonychia congenita: Thickened nails (pachyonychia), plantar keratoderma

• (E) Kindler syndrome: Poikiloderma + blistering, no bone marrow involvement

Genetic basis: Mutations in DKC1 (X-linked), TERC/TERT (autosomal), or other telomere-associated genes.

Diagnostic test: Telomere length assay (shortened telomeres in leukocytes).

Prognosis: Poor due to bone marrow failure (may require transplant).