RESUMEN
<p><b>OBJECTIVE</b>To investigate the fine needle aspiration cytology (FNAC) features and differential diagnosis of eyelid sebaceous gland carcinoma.</p><p><b>METHODS</b>Four cases of eyelid sebaceous gland carcinoma diagnosed by FNAC were reported and confirmed by biopsy. Three of the cases were in early stages with tumor sizes smaller than 10 mm in diameter and without metastasis. The smears were stained by routine H & E and SudanIII methods. The cytologic findings were described and compared to corresponding histological features, and moreover, compared to chalazion, pilomatrixoma and eyelid basal cell carcinoma.</p><p><b>RESULTS</b>Neither hemorrhage nor infection were found after the examination. Abundant cells were observed in the sebaceous carcinoma FNAC smears. Two types of tumor cells were found: one showed tumor cells differentiating toward sebaceous gland, with large pale cells and vacuolated cytoplasm, the other demonstrated poorly-differentiated cell with dark and irregular nuclei. Numerous vacuoles with inequality of size were found in cytoplasm or in background in all four cases, and the SudanIII stain showed that these vacuoles contained lipid. Some smears demonstrated cells with basaloid, fusiform or squamous features, corresponding to various histopathological types. In contrast, smears of chalazion displayed inflammatory granuloma, containing several types of inflammatory cells without malignant cells. Smears of pilomatrixoma were cellular with three cell populations, which included bland sheets of basaloid cells, nucleated basophilic cells and anucleated keratinized "ghost cells", along with calcific debris. The smears of basal cell carcinoma were typically less cellular, more tightly cohesive and had smaller clusters of uniform hyperchromatic basaloid cells without vacuolization in cytoplasm or background. Overall, the cytological features of eyelid sebaceous carcinoma were distinct from those of chalazion, pilomatricoma and basal cell carcinoma.</p><p><b>CONCLUSIONS</b>FNAC is a safe and effective approach for the diagnosis of eyelid sebaceous carcinoma and lipid stain is useful in differential diagnosis. The application of FNAC may be important in reaching an early diagnosis and initial treatment of eyelid nodule.</p>