Retrospective study of 613 canine cytologically normal bone marrows associated to altered hemograms: description, possible interpretation, and review of the principal physiological hematopoietic mechanisms

BACKGROUND: In clinical routine, it can happen that to an abnormal hemogram corresponds an unexpected cytological normal bone marrow examination that can be difficult to interpret and to manage. AIM: This cytologically retrospective study wants to evaluate a consistent number of qualitative and quantitative normal bone marrow exams according to the hematological and clinical-pathological data to judge if this normality is by itself a pathologic state. METHODS: Six hundred and thirteen bone marrow samples were examined. The bone marrow cytological examinations were performed using morphological and numerical criteria together with a complete hemogram, after the identification of clinical or hematological alterations such as multiple lymph nodes enlarged, positive leishmania serological result, staging of neoplasia, cytopenia, increased number of cells, or suspicion of malignant blood disorders. RESULTS: Of the 613 bone marrow samples evaluated, 85 (14%) were classified as normal or without cytological abnormalities; however, only 28 (33%) of those cases had a normal hemogram associated, whereas 55 (65%) had one or more cytopenia and 2 (2%) had increased blood cells count. CONCLUSION: From this study emerges that cytological bone marrow examinations without any morphological or numerical abnormalities are often associated with altered hematological exams and for this reason, they should not be considered normal and should lead to other deepened investigations.