Clinicopathologic and Ultrastructural Study of Non-HIV-related Primary Pulmonary Cryptococcosis in China: Report of 43 Cases

Objective: To clarify the clinicopathologic and ultrastructural features of primary pulmonary cryptococcosis (PC).Methods: 43 cases of PC were observed by light microscopy and histochemical staining, including mucicarmine (MC), Alcian blue (AB), periodic acid–Schiff (PAS), and Grocott methenamine–silver (GMS). Transmission electron microscopy (TEM) was performed on 11 fresh and 8 formalin-fixed specimens.Results: The detective rate of Cryptococcus neoformans (CN) by MC, AB, PAS, GMS staining, and TEM was 61.3% (19/31), 62.2% (23/37), 85.7% (30/35), 79.1% (34/43), and 89.5% (17/19), respectively. All CN detected by TEM had a capsule. Most of them possessed simple structure with undeveloped cellular organelles.Conclusion: Electron microscopy has a high rate of detecting CN. A combination of histochemical staining and electron microscopy can make an accurate diagnosis of PC.