A 74-year-old female was referred to the respiratory clinic with incidental finding of a pulmonary nodule on chest X-ray. She did not have any other respiratory symptoms. She was a non-smoker throughout her life and had no exposure to asbestos or tuberculosis. Her past medical history was significant only for chronic lymphoedema and recent hip replacement.
Subsequently , CT thorax was performed, which confirmed a 1.2 cm pulmonary nodule in the posterior segment of the left upper lobe. There was no cavitation or calcification and no discrete nodules were present in the remaining lung parenchyma. There was no mediastinal or hilar lymphadenopathy (Figure 1).
On positron emission tomography scan, the pulmonary nodule was found to be non-avid (Figure 2). Her pulmonary function tests were normal with a normal gas transfer. She was also investigated for any underlying plasma cell dyscrasias to rule out nodular amyloid deposit: no evidence was found to support it as her serum and urinary electrophoresis was negative with normal immunoglobulin levels. Biopsy of the lesion was not feasible either by bronchoscopy or by CT-guided lung biopsy. The patient underwent wedge resection as she was keen to have a definitive diagnosis and did not want to have serial imaging as part of pulmonary nodule surveillance. Microscopy of the fluid sample from the wedge biopsy showed scanty lymphocytes. No pathogenic microorganisms were found. Mycobacterial and fungal cultures were also negative.
Histology showed abundant eosinophilic material with scattered giant cell reaction. No necrosis or epithelioid granulomatous inflammation was seen. Lamellar fibrosis was evident (Figure 3).
Masson's stain confirmed hyaline lamellar fibrosis whereas Congo red stain for amyloidosis was negative (Figures 4 and 5). These features are consistent with the diagnosis of PHG.