From the Guidelines
The presence of promonocytes in a peripheral blood smear is a significant finding that typically indicates a pathological condition, such as acute or chronic myelomonocytic leukemia, monocytic leukemia, or other myeloproliferative disorders, and warrants immediate hematology consultation and further testing. According to the most recent and highest quality study 1, promonocytes are immature monocytic cells that are not typically found in peripheral circulation, and their appearance in peripheral blood suggests dysregulated hematopoiesis. The study recommends evaluating the degree of dysplasia and the presence of cytological abnormalities, including promonocytes, in blood films and marrow slides to diagnose myelodysplastic syndromes (MDS) and other myeloproliferative disorders.
Key features of promonocytes include:
- Large size (15-20 μm)
- Abundant cytoplasm
- Irregular nuclei with fine chromatin and visible nucleoli When promonocytes are detected, additional testing is recommended, including:
- Complete blood count with differential
- Bone marrow aspiration and biopsy
- Flow cytometry
- Cytogenetic studies The percentage of promonocytes and other immature cells helps in disease classification and prognosis assessment, and regular monitoring of promonocyte counts is essential for tracking disease progression and treatment response in affected patients, as noted in 1 and 1. However, the most recent study 1 provides the most up-to-date guidance on the diagnostic workup and management of patients with promonocytes in their peripheral blood smear.
From the Research
Significance of Promonocytes in Peripheral Blood Smear
- Promonocytes are immature white blood cells that can be found in peripheral blood smears, and their presence can be significant in the diagnosis of certain hematologic disorders 2.
- The enumeration of blasts and promonocytes is essential for the World Health Organization (WHO) classification of myelomonocytic neoplasms, and the accuracy of distinguishing between these cells is crucial for diagnosis 2.
- A study found that hematopathologists achieved a good concordance rate in categorizing patients according to the sum of blasts and promonocytes in peripheral blood, with a Fleiss' kappa value of 0.949 2.
- The presence of promonocytes in peripheral blood smears can be an important parameter in distinguishing atypical chronic myeloid leukemia from chronic granulocytic leukemia and chronic myelomonocytic leukemia 3.
- The evaluation of promonocytes in peripheral blood smears can be useful in conjunction with bone marrow aspirate and trephine biopsy findings to aid in the diagnosis of hematologic disorders 3.
Clinical Relevance
- The presence of apoptotic leukocytes, including promonocytes, in peripheral blood smears can be related to the severity of disease and may help in differential diagnosis 4.
- A study found that the most common diagnosis associated with the presence of apoptotic leukocytes was infection, and that apoptosis in lymphocytes was associated with diabetes mellitus, glucocorticoid administration, and neoplastic diseases 4.
- The evaluation of peripheral blood smears, including the presence of promonocytes, can be an important skill for hematologists and oncologists to guide diagnostic evaluation and further testing 5.
Diagnostic Utility
- Peripheral blood smear review, including the evaluation of promonocytes, can lead to further testing and diagnosis of hematologic disorders 5.
- A study found that peripheral blood smear review led to further testing in 41.4% of cases, and that a bone marrow biopsy was performed in 11.5% of cases where a peripheral blood smear was reviewed 5.
- The combination of blasts and promonocytes into a single category can be a useful practice in the diagnosis of myelomonocytic neoplasms 2.