Diagnosis of pulmonary lymphangioleiomyomatosis by HMB45 in surgically treated spontaneous pneumothorax.

Pulmonary lymphangioleiomyomatosis (PLAM) is a rare disease with poor prognosis, characterized by an abnormal proliferation of smooth muscle. The patients are females and recurrent pneumothorax is a frequent complication. HMB45 is a monoclonal antibody with specific immunoreactivity for malignant melanoma. Recently, it was reported that some of the smooth muscle cells in PLAM had reactivity for HMB45. The aim of this study was to assess the sensitivity and specificity of HMB45 for the diagnosis of PLAM in cystic pulmonary diseases that cause recurrent pneumothorax. We compared immunoreactivity of the specimens obtained by open lung biopsy at surgical resection of bullae in 72 patients. The specimens of five females with PLAM, one female with suspected PLAM, 49 patients with primary spontaneous pneumothorax (19 females and 30 males), four with pulmonary eosinophilic granuloma (2 females and 2 males), seven with pulmonary emphysema (7 males), and six with idiopathic pulmonary fibrosis with apical bullous change (2 females and 4 males) were stained with HMB45 and anti-smooth muscle actin. All PLAM cases had HMB45 positive cells, which also stained with anti-smooth muscle actin. The biopsy specimens of a PLAM suspected case also stained with HMB45. None of the specimens from other diseases reacted with HMB45. HMB45 appears to provide a highly specific and highly sensitive diagnosis for PLAM in females. It may also be useful in patients with subtle smooth muscle proliferation. where the diagnosis of PLAM is difficult to confirm by conventional histological examination.