Objective: To establish the cytologic and immunocytochemical features of lymphangioleiomyomatosis (LAM) cell clusters (LCCs) and to clarify its diagnostic significance for LAM.
Study design: We evaluated 17 samples of LAM-associated chylous effisions from 13 patients with LAM. We performed Papanicolaou staining and immunocytochemistry for muscular antigens, melanoma-related antigens, female 'hormone receptors and markers for lymphatic endothelial cells (LECs).
Results: The cytologic features of LCCs were a well-organized, globular cluster consisting of LAM cells enveloped by LECs. The LAM cells were observed to form a tightly cohesive core and had a moderate nuclear/cytoplasmic ratio. These are distinct characteristics from cancer cell clusters. Immunocytochemical examinations revealed the LAM cells to be positive for muscular antigens, melanoma-related antigens and progesterone receptor, but only 2 of 7 specimens were positive for estrogen receptor. The surface monolayer cells were confirmed to be immunopositive for various LEC markers. Ultrastructural study confirmed that LCCs were covered by LECs.
Conclusion: LCCs were detected in all LAM-associated chylous effusion samples. The cytologic and immunocytochemical examinations of chylous effusions are thus considered to have diagnostic significance for LAM that may therefore enable patients to avoid undergoing such invasive tests as lung biopsies.