DiffQuik

DiffQuik is a rapid, three-step Romanowsky-type stain used in cytology and hematology to stain cells on air-dried or fixed slides. It is widely used in clinical laboratories for quick assessment of cytology specimens and bone marrow.

The method uses three solutions: a methanol-based fixative to preserve cellular morphology, followed by two aqueous counterstains that differentially color cellular components. Nuclei typically appear blue to purple, cytoplasm pink to orange, with eosinophilic granules and certain cytoplasmic features highlighted.

Applications include staining of prepared smears from fine-needle aspiration biopsies, touch imprints, effusion fluids, body cavity fluids, peripheral blood smears, and bone marrow aspirates, especially for rapid preliminary assessment.

Advantages include speed, simplicity, low cost, and suitability for rapid triage of samples at the point of collection. It is compatible with routine lab workflows and requires minimal equipment.

Limitations include that color balance and staining quality can vary between lots and manual technique, and the stain may provide less detail for nuclear morphology compared with Wright-Giemsa. It is not ideal for formalin-fixed paraffin-embedded tissues or for downstream molecular analyses, and it uses methanol, which requires appropriate safety handling.