Giant Cell Lesions of Lungs: A Histopathological and Morphometric Study of Seven Autopsy Cases

Abstract

Introduction: Macrophages undergo fusion to form multinucleated giant cells (MGC) in several pathologic conditions. The exact mechanism of their generation is still unclear. MGC are a common feature of granulomas that develop during various inflammatory reactions.

Aim: To study the histopathological features of giant cell lesions in lungs and correlate the characteristics of giant cells with other histopathological findings. Also, to determine the utility of morphometry to differentiate foreign body and Langhans MGC.

Materials and methods: Seven cases were analysed. Specimen of lungs was grossed, sectioned and processed. Routinely, tissue sections were stained by Haematoxylin and Eosin (H&E) stain. Polarizing microscopy and special stains were employed in selected cases. Granulomas and MGC were counted and measured. Several other parameters like location, distribution, type and number of MGC, associated predominant inflammatory component and nature of granulomas were analysed.

Results: Five patterns of lesions were observed in seven cases. Aspiration pneumonia was seen in three cases (42.85%) and constituted the most common pattern. However, aspiration pneumonia as the only cause of MGC was seen in only one case (14.28%). Pulmonary tuberculosis and asteroid bodies constituted two cases (28.57%) each. Cryptococcal pneumonia and cholesterol clefts constituted one case (14.28%) each. Crypococci were demonstrated to be positively birefringent by polarized microscopy on Ziehl-Neelsen stained sections. Based on statistical analysis of morphometric data, a new index (NP index) was proposed to statistically categorize MGC into foreign body type and Langhans type. NP index value of ≤0.016 was found to be statistically significant (p<0.005) in foreign body MGC. It had high sensitivity and efficacy.

Conclusion: MGC may not be always associated with granulomas. The mechanisms that lead to the occurrence of MGC, independent of granuloma needs to be elucidated. Morphometry may serve as a useful aid. But a pathologist has to rely on the morphological details to categorize MGC.

Keywords: Birefringent; Cryptococci; Granulomas; Multinucleated giant cells.

[Table/Fig-3]:

Microphotograph of tissue section of lung displaying Langhans type (thick arrow) and foreign body type of giant cells (thin arrow) in a case of pulmonary tuberculosis (case 3). (H&E, X200)

[Table/Fig-4]:

Microphotograph of tissue section of lung displaying acid fast bacilli in a case of pulmonary tuberculosis (case 3). (ZN, X1000)

[Table/Fig-5]:

Microphotograph of tissue section of lung displaying foreign body type of giant cells (arrow) with asteroid body (case 5). (H&E, X400)

[Table/Fig-6a]:

Microphotograph of tissue section of lung displaying Langhans type of giant cell (thick arrow) and Cryptococci (thin arrow) in a case of cryptococcal pneumonia (case 1). (H&E X200)

[Table/Fig-6b]:

Microphotograph of tissue section of lung displaying capulated cryptococci in a case of cryptococcal pneumonia (case 1). (PAS, X200)

[Table/Fig-7a]:

Microphotograph of tissue section of lung displaying cryptococci (arrows) in a case of cryptococcal pneumonia (case 1) before polarization. (ZN, X200)

[Table/Fig-7b]:

Microphotograph of tissue section of lung displaying birefringent cryptococci (arrows) with maltese cross appearance in a case of cryptococcal pneumonia (case 1) after polarization. (ZN, X200)

[Table/Fig-8]:

Microphotograph of tissue section of lung displaying aggregates of cholesterol clefts with surrounding foreign body giant cells (arrow) in case 2. (H&E, X100)

[Table/Fig-9]:

Microphotograph of tissue section of lung displaying foreign body giant cells with engulfed cholesterol cleft (arrow) in case 2. (H&E, X200)