Double Feature

Case Challenge (Taken from Medscape)

A 10-year-old boy who emigrated from Guinea, West Africa, 6 months ago presents with splenomegaly lasting several years. His mother reports that he had lived in a small village in Guinea with his grandmother since birth. Starting at age 5 years, the patient began complaining of left-sided abdominal pain. A workup performed in Guinea was inconclusive, according to his grandmother.

He was the product of a full-term vaginal delivery and weighed 9 lb (4 kg) at birth. Although the patient has always been small for his age (third to fifth percentile), he has cognitively developed appropriately alongside his peers.

He has no significant medical history. The patient has two younger female siblings who are currently residing in the United States; both are reportedly healthy. Routine vaccinations are up to date.

Physical Examination and Workup

Upon physical examination, a review of systems is negative for fevers, rashes, fatigue, seizures, jaundice, vomiting, diarrhea, behavioral changes, easy bruising, and musculoskeletal or visual disturbances.

His weight is 53.5 lb (24.25 kg), which puts him beneath the fifth percentile for his age. His height is 4'1" (125 cm), which also is beneath the fifth percentile for his age. A head, eyes, ears, nose, and throat examination reveals anicteric, moist pink conjunctiva and shoddy mobile anterior cervical lymphadenopathy (largest, <1 cm). He has no rash, edema, joint swelling, warmth, or tenderness.

His lungs are clear to auscultation. Bilateral breath sounds are equal. His abdomen is soft and distended, with normal bowel sounds. His liver is 3 cm below the right costal margin. It is smooth, nontender, and not firm. His spleen is palpable 10 cm below the left costal margin and is 6 cm wide. It is nontender. No other tenderness or peritoneal signs are noted.

Laboratory findings are as follows:

• White blood cell (WBC) count—5.7 x 109/L

• Hemoglobin level—9.7 g/dL (hemoglobin electrophoresis is normal)

• Hematocrit level—30.4%

• Mean corpuscular volume—77.5 fL/red cell

• Platelet count—128 x 109/L

• Neutrophil count—41.9%

• Lymphocyte count—40.1%

• Eosinophil count—8.9%

• Reticulocyte count—7%

Comprehensive metabolic panel results are as follows:

• Sodium level—138 mEq/L

• Potassium level—3.7 mEq/L

• Chloride level—103 mEq/L

• Carbon dioxide level—27 mEq/L

• Glucose level—101 mmol/L

• Blood urea nitrogen level—9 mmol/L

• Creatinine level—0.34 mg/dL

• Total protein level—7.9 g/dL

• Albumin level—4.5 g/L

• Calcium level—10.2 mg/dL

• Total bilirubin level—1.9 mg/dL

• Direct bilirubin level—0.3 mg/dL

• Alkaline phosphatase level—206 IU/L

• Aspartate aminotransferase level—26 IU/L

• Alanine aminotransferase level—13 IU/L

Urinalysis reveals clear urine with a trace of blood. It is negative for urobilinogen, nitrate, leukocyte esterase, glucose, and ketones. Occasional bacteria is noted, with no other organisms seen. A urine culture reveals no growth. Other urinalysis findings are as follows:

• Specific gravity—1.015

• pH level—6.5

• Protein level—100 mg/dL

• Red blood cell (RBC) count—9 RBC/high-powered field (HPF)

• WBC count—40 WBC/HPF

Stool tests negative for the presence of blood. An immune and metabolic workup is negative for antinuclear antibody and rheumatoid factor. Ferritin level is normal, as is the urine glycosaminoglycan level. A T-cell subset panel reveals normal findings. Other findings are as follows:

• Erythrocyte sedimentation rate—55 mm/hr

• C-reactive protein level—<4 mg/L

• Lactate dehydrogenase level—245 IU/L

• Immunoglobulin (Ig) M level—156 mg/dL

• IgG level—2053 mg/dL

• IgA level—75.9 mg/dL

• IgE level—355 mg/dL

Further evaluation looked at exposure to infectious agents. The patient's Epstein-Barr virus results are negative. Hepatitis C antibody, hepatitis B surface antigen, and HIV tests are negative. Quantiferon testing for latent tuberculosisis negative. A malaria blood smear is also negative. The patient tests negative to the following organisms:

• Schistosoma

• Strongyloides

• Echinococcus

• Cryptosporidium

• Giardia

By abdominal ultrasonography, the patient's liver is 12.1 cm with normal echogenicity, no nodularity, and no intrahepatic or extrahepatic ductal dilatation. The common bile duct is 2.4 mm. No mass is identified. His spleen is 15 cm, with tortuosity and dilatation of the splenic vasculature.

Which of the following is the most likely diagnosis?

Sickle cell disease

Chronic malaria

Leukemia

Lymphoma

Lipid storage disease

Drumroll please.....

This child was a recent immigrant from Guinea, where malaria is endemic. Despite negative smears for malaria, a high index of suspicion prompted molecular testing (polymerase chain reaction [PCR]), which was positive for Plasmodium falciparum. P falciparum is responsible for more than 85% of endemic malaria species in Guinea.

Also:

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