Cytoarchitectural findings in the diagnosis of primary soft tissue tumors

To review the major cytologic and architectural criteria in the diagnosis of primary soft tissue tumors, highlighting the importance of clinical correlation and the value of ancillary methods.

Given the variety and complexity of clinicopathologic entities, the initial approach is based on pattern analysis. Six basic categories are established as a function of cell shape, stromal characteristics and resemblance to normal tissue.

First, in myxoid-rich matrix tumors, special attention should be paid to lipoblasts, ganglion type, stellate cells and metachromatic fibrillar matrix. Second, in round cell tumors the following cytoarchitectural findings are of special interest: atypical rhabdomyoblasts, atypical lipoblasts, neuroblast rosettes, cytoplasmic glycogen, melanin pigment, islets of mature cartilage, hyaline cytoplasmic inclusions and fragments of connective tissue closely associated with round cells. Third, in spindle tumors the most important cytoarchitectural findings are: biphasic cellularity; elongated, buckled or wavy, tapered nuclei; nuclear palisades; straight, elongated, blunt-ended nuclei; melanotic pigment; storiform pattern; tissue fragments with collagen fibers or degenerated elastin; intracytoplasmic hyaline globules; and scattered spindle cells in a background of red blood cells. Fourth, in pleomorphic tumors specific typing is often difficult, if not impossible, since cells display few or no differential features. Fifth, in epithelial like cell tumors the cytologic findings of major diagnostic interest are: melanin deposits, crystalline inclusions, intracytoplasmic lumina, anisonucleosis and nuclear cytoplasmic inclusions. Last, in maturelike cell tumors, the architectural pattern resembles that of mature tissues.

Although cytologic analysis of primary soft tissue tumors is hampered by the paucity of diagnostic findings, the establishment of clinicocytologic correlations, taking into account architectural patterns, cytologic details and clinical characteristics of the lesion, allows precise diagnosis of a significant number of tumors. Application of new techniques (immunocytochemistry, electron microscopy and cytogenetics) to cytologic aspirates has prompted a substantial reduction in the number of doubtful clinicocytologic diagnoses and considerably broadened the diagnostic spectrum.