2025 – PAGE 109 – ALLERGY & IMMUNOLOGY

MNEMONICS & PEARL FOR SCID AND WISKOTT-ALDRICH

• Skidding Ostrich—Read about the disorders first.
• Imagine that a PCP’s office has a small, yellow, 3-foot slip’n’slide for babies. One of the babies loves OSTRICHES. There’s a drawing of an OSTRICH at the end of the slide against a wall (W-All). The mom gives the baby a little push and the baby SCIDs (on his butt) right into the drawing and the baby’s head erases the NADS right off of the OSTRICH! Now the OSTRICH and the SCIDing baby boy have NO NADS/NODES.
• SCID and OSTRICH should link the two diseases in your mind. They are both combined T and B cell deficiencies. The “W-All” is another reminder of WiXott Aldrich (the X in WiXott refers to the fact that it’s X-linked). BOTH disorders lack the presence of lymphadenopathy, and both have a small thymus (so a BMT helps).
• PEARL: TheLEUKOcyte count may be NORMAL because of a higher number of neutrophils. Any time you see a low ALC or the word LYMPHOpenia, you should think about T-CELL or COMBINED disorders because MOST LYMPHOcytes ARE T-CELLS!

(DOUBLE TAKE) WISKOTT-ALDRICH SYNDROME

For Wiskott-Aldrich syndrome, look for a patient with a history consistent with the triad of SMALL Thrombocytes, frequent Infections, and Eczema. Platelets can be small in size and/or number. This is an X-linked disorder, so it will only be found in MALES. Patients develop both T and B cell problems as they age. IgM is usually LOW, while IgA may be HIGH. A history may include findings such as petechiae, bloody diarrhea, bloody circumcision, eczema, and/or otitis media. There is an increased risk of lymphoma in the third decade of life. A BMT is curative.

• MNEMONIC: Wiskott Aldrich = wiXotT ostrich = Imagine a WISe OSTRICH wearing some nerdy black glasses, a tux, and a TIE with the word “T-I-E” spelled down the front.
• MNEMONIC: (image)

• • KEY: X-linked, small T = Represents small platelets (low MPV) and Thrombocytopenia, I = Infections, E = Eczema, Mirrored W = M and arrows show that IgM is low, Duplicate A refers to IgA, and arrows show that IgA levels are increased.
• PEARL: In Idiopathic Thrombocytopenic Purpura (ITP), platelets are BIGGER.
• PEARL: Universal newborn screening for SCID is done in all states.