Low Mitotic Index - DDx

· Hypocellular sample

· Inadequate amount of specimen used to initiate culture

· Hypocellular marrow (correlate with smear)

· Post-chemotherapy

· Slowly dividing malignancy (ex. CLL, hairy cell leukemia)

· Inappropriate tissue

· Media expired or contaminated

· For PHA stimulated:

· PHA concentration too low or reagent expired

· Poor response to PHA due to hematologic disease

· For thymidine synchronized cultures:

· Thymidine exposure too short (not enough cells have accumulated in S-phase

· Hypotonic made up incorrectly or timed too long (cells have lysed)

· Colcemid not added or timed too short

References:

· Barch MJ, Knutsen T, Spurbeck JL. The AGT Cytogenetics Laboratory Manual. 3rd ed. Lippincott Williams & Wilkins; 1997.