In this review, we focus on the heterogeneity of interstitial lung diseases detected in patients with collagen vascular diseases. By recognizing the heterogeneity of histopathology and comparing them with bronchoalveolar lavage fluid cell findings, we can understand profiles of lung inflammation and injuries and fibrosis in collagen vascular diseases. We focus on the significance of lung lymphocytosis in the lesions of patients with collagen vascular diseases, looking most closely at lesions in unusual interstitial pneumonia. The current understanding of immunopathogenesis and immunopathological findings is reviewed in the context of subsets of collagen vascular diseases.