Figure 2

Different degrees of small pulmonary vasculitis were showed under HE staining. A, Vessel wall was infiltrated by lymphocytes, but the lumen is still maitain without obstruction(100×); B, Epithelioid granuloma invaded small vessel wall, broke into the lumen, more than 60% of the lumen was obstructed (100×); C, Last stage of epithelioid granulomatous vasculitis with thickening vessel wall as well as severe narrow lumen. Epithelioid granuloma invaded the vessel wall with messed vascular structures, lumen atresia (200×).