Index of Suspicion

Case 1 Presentation

A 2-month-old girl is admitted to the hospital because of a 2-day history of fever, lethargy, decreased appetite, and neck masses. She has had an intermittent but progressively worsening rash since birth, which was normal. She has had mild-to-moderate seborrheic dermatitis on her scalp and forehead. Three weeks ago, she was admitted for a rash and fever, which were treated as impetigo and cellulitis.

On physical examination, the infant is irritable. Her temperature is 101°F (38.4°C), respiratory rate is 60 breaths/min, heart rate is 120 beats/min, and blood pressure is 90/60 mm Hg. Her skin shows scattered, hypopigmented, scaly ovoid lesions measuring 0.2 to 1 cm and multiple erythematous macular lesions with two necrotic areas from the head to the pelvis. Thick, greasy, crusted lesions are noted on her scalp. She has multiple 2- to 3-cm firm, nontender anterior and posterior cervical lymph nodes bilaterally. Her liver and spleen are enlarged and 4 cm and 6 cm below the coastal margins, respectively.

Laboratory findings include: Hgb, 4.8 g/dL (48 g/L); mean cell volume, 90 fL; mean cell hemoglobin, 26 pg; mean cell hemoglobin concentration, 29%; WBC count, 14.5×10³/mcL (14.5×10⁹/L) (36% neutrophils, 53% lymphocytes, 8% monocytes, 3% eosinophils); platelet count, 204×10³/mcL (204×10⁹/L); reticulocyte count, 10% (0.1); and C-reactive protein, 9.8 mg/L. Coagulation studies, serum electrolyte concentrations, and liver enzyme values are normal. A chest radiograph shows bilateral increased lung markings. Her bone marrow biopsy yields normal results. Bone survey reveals a single septal lucency in the right femur measuring 5 mm. Skin and lymph node biopsies are performed, and the histologic findings confirm the diagnosis.

Case 2 Presentation

A 5-month-old girl presents with a 1-week history of episodes described as sudden flexion of the head, neck, and torso, with her upper limbs flaring outward and inward, …