Cytologia nowotworów mezenchymalnych

Cytology of mesenchymal neoplasms

Cells of mesenchymal origin include those that form connective tissue, lymphatic and blood vessels, and hematopoietic cells. Cytologically, the hematopoietic neoplasms are grouped separately as round cell tumors because of the cells’ discrete appearance. Cytologic samples from normal mesenchymal tissue are expected to have low cellularity, and benign mesenchymal tumors also exfoliate low numbers of cells. By contrast, malignant mesenchymal tumors can exfoliate large numbers of cells resulting in highly cellular slides.

General cytologic features 

In general, mesenchymal cells in cytologic samples appear individualized or loosely aggregated. Cell shape is usually elongated or spindled, with tapered or fusiform cytoplasm that often has indistinct borders. Nuclei vary from round to oval to rod-shaped. Some types of mesenchymal tumors produce an extracellular matrix that can be visualized surrounding cells, especially within cellular aggregates. In addition to the neoplasms listed above, melanoma and histiocytic sarcoma may be considered mesenchymal tumors. Melanoma is often described as „the great imitator” because of the variety of morphologic presentations it can have in cytologic samples. Histiocytic sarcoma, a neoplasm that can arise from either dendritic cells or macrophages, most often has a discrete cell appearance on cytology, but occasionally the cells can appear spindled.

Criteria of malignancy 

When evaluating any cytology sample from a mass lesion suspected to be neoplastic, it is important to keep some basic principles in mind. Remember that cytologic interpretations are based on populations of cells; slides must contain sufficient numbers of cells that are well-spread out and well-stained in order to have confidence in the interpretation. Particularly when considering mesechymal neoplasia, remember that reactive or hyperplastic mesenchymal populations can show atypia suggestive of neoplasia....