Cytology of Cutaneous and Subcutaneous Lesions

Cytology of cutaneous and subcutaneous lesions

Cutaneous and subcutaneous lesions are very common in veterinary private practice. Cytology is a fast, inexpensive and relatively simple technique, which can be useful in diagnosing these lesions. During this lecture the cytology of an interesting selection of these lesions will be presented. Practitioners just beginning with cytology and more experienced ones will be captivated.

Cutaneous tumors
Different type of round cell tumors may be found cutaneous displaying characteristics from hematopoietic tissue origin: high cellularity, individual cells, small to medium sized, distinct cell borders and a round nucleus. To this group of also called “discrete cell neoplasms” belong mast cell tumors, malignant lymphomas, cutaneous plasmacytomas, histiocytomas, melanomas and transmissible venereal tumors. Secondary infection or inflammation makes it difficult to determine primary cause of the process. Mast cell tumors contain many purple cytoplasmic granules, which can obscure the round nucleus. Beware of occasional non-staining granules in mast cells by Diff-Quik or Hemacolor® making a diagnosis difficult. Large numbers of eosinophils and fibroblasts can also be present. Melanoma cells meet the criteria of discrete cell tumors and contain blue to greenish- black cytoplasmic granules however they are not originated from hematopoietic origin and can also display features of mesenchymal and epithelial cells. Malignant lymphoma displays a homogeneous population of lymphocytes without reactive features as heterogeneous population of lymphocytes and without plasma cells or eosinophils. Plasmacytomas may contain typically plasma cells or less differentiated. Histiocytomas displays large cells with pale grey-blue cytoplasm. Transmissible venereal tumors show anisocytosis, cytoplasmic vacuoles, round to oval eccentric nuclei, anisokaryosis and variable N/C ratio. […]