Background: Pulmonary lymphangiomyomatosis (P-LAM) is a rare disease, characterized by an abnormal proliferation of smooth muscle throughout the lung and occurring in females of reproductive age. The typical clinical picture in P-LAM is progressive dyspnea, often punctuated by episodes of chylothorax or pneumothorax, with eventual death from respiratory failure. The definitive diagnosis is usually performed on open lung biopsies.
Case: The cytologic findings in a chylous pleural effusion from a patient with P-LAM are presented. The effusion contained an abundance of globular cell clusters composed of two distinct cell types, inner core spindle cells and surface flat cells. Immunocytochemical examination revealed that the core cells were derived from immature smooth muscle cells and the surface cells from endothelium. Histologic examination of the excised specimen showed the typical findings of P-LAM, and the dilated peripheral lymphatics contained cell clusters similar to those in the pleural effusion. The cell clusters in the lymphatics in the P-LAM lung tissue appeared to have ruptured into the thoracic cavity.
Conclusion: Cell clusters seem to be pathognomonic of P-LAM, and cytologic examination can obviate the need to perform open lung biopsy to confirm the diagnosis.