🩸 Leukopenia · Neutropenia · Infection · Autoimmune · Kostmann · Cyclic · Vitamin B12

Schwartz Clinical Handbook — Chapter 49 · Absolute neutrophil count (ANC) · Sepsis · Drug‑induced · Autoimmune neutropenia · Cyclic neutropenia · Kostmann syndrome

Select ANC, fever, oral ulcers, recurrent infections, drug history, ethnicity (African ancestry), and CBC trends → differentiate transient viral neutropenia from autoimmune neutropenia, cyclic neutropenia, Kostmann syndrome, drug‑induced, marrow failure, or megaloblastic anemia.
⚠️ Red flags: ANC <500, fever, septic appearance → urgent antibiotics, hospital admission.

📋 Step 1 — ANC, fever & infection history
📌 Diagnostic impressions
📖 Schwartz Ch 49

Select ANC, fever, oral ulcers, cellulitis, perirectal abscess, drug history, ethnic background (African ancestry: normal ANC 1000‑1500), and serial CBC pattern → differentiate transient viral neutropenia, autoimmune neutropenia, cyclic neutropenia, Kostmann syndrome, drug‑induced, marrow failure, nutritional deficiency (B12, folate).

✔️ ANC <1500 = neutropenia; severe <500.
✔️ Viral neutropenia: resolves in 2‑6 weeks.
✔️ Autoimmune neutropenia: isolated neutropenia, anti‑neutrophil antibodies, mild infections.
✔️ Cyclic neutropenia: 21‑day cycles, oral ulcers, fever.
✔️ Kostmann: congenital, ANC <200, severe infections from infancy.
📘 Schwartz pearls (Chapter 49)
• ANC = WBC × (%segs + %bands).
• Febrile neutropenia (ANC <500) → blood culture, IV antibiotics (piperacillin‑tazobactam, cefepime).
• G‑CSF indicated in severe congenital neutropenia (Kostmann).
• Check B12, folate, copper in unexplained neutropenia.
• Autoimmune neutropenia usually benign, resolves by age 3‑5y.