Asteroid bodies and other cytoplasmic inclusions in necrobiotic xanthogranuloma with paraproteinemia

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

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.

Aggressive histiocytic disorders that can involve the skin

Histiocytoses are a heterogeneous group of disorders that are characterized by the proliferation and accumulation of reactive or neoplastic histiocytes. Three classes of histiocytoses have been defined: class I, Langerhans cell disease; class II, non-Langerhans cell histiocytic disease without features of malignancy; and class III, malignant histiocytic disorders. Although the disorders in classes I and II usually have a benign appearance on histology and are commonly non-aggressive and self-healing, some can cause debilitating or even fatal outcomes. Such cases beg the question: what stimulates aggressive behavior of a classically benign disease? New molecular information may now provide insight into the driving force behind many of the aggressive histiocytoses. In this article, we review Langerhans cell disease and seven aggressive histiocytoses that can involve skin, discuss histologic features that may forecast a poor prognosis, and discuss the molecular findings that help to explain the pathophysiology of these aggressive histiocytic disorders.

Necrobiotic xanthogranuloma presenting as a solitary tumor

We report on a 60-year-old overweight white woman who presented with an asymptomatic flat, hard, yellow-brown subcutaneous plaque on her right hip. A total excision was performed. Histopathologic examination showed all the major features of a necrobiotic xanthogranuloma (NX) involving the entire dermis and subcutis, including areas of necrobiosis with cholesterol clefts, granulomatous infiltrate with some bizarre giant cells, numerous Touton cells, foamy cells, lymphoid follicles with germinal centers, foci of plasma cells, and "Touton cell panniculitis." A laboratory investigation revealed only slightly increased titers of cholesterol, strong positivity of anti-Borrelia antibodies, and diffuse skeletal osteoporosis with fractures of seven vertebrae. After 4 years of close follow-up, the osteoporosis was improved, and there were no signs of paraproteinemia, malignancy, or new skin lesions. The authors suggest that this case could represent a solitary clinical variant of NX without paraproteinemia.