CT differentiation of enlarged mediastinal lymph node due to anthracosis from metastatic lymphadenopathy: a comparative study proven by endobronchial US-guided transbronchial needle aspiration

Abstract

Purpose: Anthracosis often results in mediastinal nodal enlargement. The aim of this comparative study was to evaluate if it is possible to differentiate endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) proven anthracotic lymph nodes from malignant lymph node enlargement by means of multislice computed tomography (MSCT).

Methods: We compared the MSCT findings of 89 enlarged lymph nodes due to anthracosis with 54 malignant lymph nodes (non-small cell lung cancer 75.9%, small cell lung cancer 18.5%, and non-Hodgkin lymphoma 5.6%). The lymph nodes were assessed for density (calcification, fat, and necrosis), shape (oval, round), contrast enhancement, and contour (sharp, ill-defined).

Results: Malignant lymph nodes showed significantly greater axis diameters (P < 0.001). Both anthracotic and malignant nodes were most often oval (86.5% of all malignant nodes vs. 81.5% of all anthracotic nodes, P = 0.420) and showed confluence in a remarkable percentage (28.1% vs. 42.6%, P = 0.075). Anthracotic nodes showed calcifications more often (18% vs. 0%, P < 0.001). Malignant lymph nodes showed a significantly greater short and long axis diameter (P < 0.001), and they had a higher frequency of ill-defined contours (27.8% vs. 2.2%, P < 0.001) and contrast enhancement (27.8% vs. 5.6%, P < 0.001). Nodal necrosis, which appeared in one third of the malignant nodes, was not observed in anthracosis (35.2% vs. 0%, P < 0.001). Confluence of enlarged lymph nodes was seen in malignant lymph nodes (42.6%), as well as in lymph node enlargement due to anthracosis (28.1%, P = 0.075).

Conclusion: Our results show that there are significant differences in MSCT findings of malignant enlarged lymph nodes and benign lymph node enlargement due to anthracosis.

Figure 1.

EBUS-TBNA in an enlarged anthracotic lymph node. Cytologic specimen shows a fibrous fragment of a lymph node with deposition of anthracotic pigment in macrophages and in the extracellular space. Papanicolaou staining, 12×10.

Figure 2.

CT image reveals confluence of enlarged lymph nodes in ATS regions 4R/10R and 4L/10L, some of them showing subtle calcifications.

Figure 3.

CT image reveals an enlarged lymph node in ATS Region 7 showing central colliquation. Pulmonary mass is seen in the right lower lobe (EBUS-TBNA confirmed small-cell lung carcinoma).

Figure 4.

CT image demonstrating extensive calcifications in enlarged lymph nodes with EBUS-TBNA confirmed anthracosis.