Early Stages of Hyaline Membrane Formation Detected in Alveolar Mouths in Diffuse Alveolar-Damage-Associated Diseases: A Detailed Immunohistochemical Study.

To study the early stages of hyaline membrane (HM) formation, diffuse alveolar damage (DAD) was thoroughly investigated using immunohistochemical methods in 15 autopsy cases, which consisted of various types of interstitial pneumonias and pulmonary diseases derived from nonmalignant or malignant diseases. Alveolar mouths (AMs) that were presumed to be normal were ultrastructurally examined in detail, by using pulmonary tissues in the pneumothorax. It is interesting to note that during the initial stages of HM formation in AMs, fragmented eosinophilic masses were closely attached to AMs as irregular fragments or by a cap-like structure. The ultrastructure revealed some distance between the capillary spaces and surface epithelium of the AMs, indicating that the epithelial cells at the AMs might be often easily damaged even by minor stimuli; they can be considered as "locus minoris resistentiae." HMs were found to be formed initially at the site of AMs derived from fragmented eosinophilic masses in not only pulmonary but also extrapulmonary diseases, including both nonmalignant and malignant diseases. These irregular eosinophilic masses, representing the early shape of HMs, were immunohistochemically positive for the epithelial membrane antigens, namely, surfactant protein A and factor VIII antigen, and occasionally for KL-6 and cytokeratins. These results suggested that fragmented irregular masses represent the initial phase of HM formation. Five of 15 cases were focally negative for KL-6 at the initial irregular mass of HMs. Because KL-6 is one of the fundamental components of pulmonary surface elements, it needs to be studied further by detailed clinicopathological examination.

Clinicopathological findings of four cases of pure influenza virus A pneumonia.

OBJECTIVE: The purpose of this study was to perform clinicopathological evaluations of patients with pure influenza A virus pneumonia. METHODS: We performed clinicopathological analyses of four cases of pure influenza A virus pneumonia. Patients Among the four cases, three were caused by the pandemic (H1N1) 2009 virus. Three patients were analyzed during autopsy, and one underwent transbronchial lung biopsy. RESULTS: We suggest that the interval between influenza virus A pneumonia onset and our analysis affected the pathological findings. Diffuse alveolar damage was observed during the acute phase. After ten days, organizing pneumonia and marked proliferation of premature type II alveolar epithelium were observed. Clinically, intra-alveolar hemorrhage was observed in two patients. Pathologically, hyaline membrane formation and intra-alveolar hemorrhage were observed in all cases. CONCLUSION: Severe epithelial damage was determined as the main mechanism of respiratory failure caused by influenza A virus pneumonia.

[Efficacy of three-dimensional computed tomography for evaluating airway tract involvement in patients with relapsing polychondritis].

The airway tract involvement is known to be one of the most important prognostic factors in patients with relapsing polychondritis (RP). Sequential evaluations of airway tract involvements are necessary, however, the insertion of flexible bronchoscope into the affected airway tract may exacerbate their airway tract stenosis. Three-dimensional computed tomography (3D-CT) showed stenosis of the trachea and bilateral main bronchi in 2 patients with RP. 3D-CT is an effective non-invasive method for evaluating airway tract involvement in RP.

Immunohistochemical and immunoelectron microscopic studies of the localization of KL-6 and epithelial membrane antigen (EMA) in presumably normal pulmonary tissue and in interstitial pneumonia.

To clarify the localization of KL-6 and epithelial membrane antigen (EMA) in human lungs, immune reactions to antibodies to these factors were examined in detail at light and electron microscopic levels. Immunohistochemical investigation was performed in 17 cases of usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP), hypersensitivity pneumonitis (HP), collagen vascular disease-associated interstitial pneumonias (CVD-IP), viral pneumonia, and bronchobronchioloectasis, as well as in 10 cases of presumably normal pulmonary tissue resected as a result of spontaneous pneumothorax. Immunohistochemical study revealed similar discontinuous linear or dome-shaped positive patterns restricted to type II alveolar cells in presumably normal tissue and only some regions of interstitial pneumonia. In sharp contrast, immune reactions with each of the two antibodies yielded a continuous linear pattern surrounding damaged areas in most regions of interstitial pneumonias and some normal areas as well. Staining for EMA antibody was negative in some regenerating alveolar and bronchial cells in regenerating foci in interstitial pneumonias, although staining for KL-6 antibody was always positive in these cells. Immunoelectron microscopic studies demonstrated similar positive reactions with both antibodies on the surface of alveolar epithelial cells in three of the cases examined, with surface positive granules 100-200 nm in diameter. Thus, although staining for both KL-6 and EMA antibodies exhibited discontinuous positivity restricted to type II alveolar cells in nondamaged regions, immune reactions were continuous and linear in pattern in or around damaged areas of the lungs at both light and electron microscopic levels, probably as a consequence of cell-surface barrier function. These findings in pulmonary tissue might be evidence of defense functions.

Immunohistochemical distribution of SP-D, compared with that of SP-A and KL-6, in interstitial pneumonias.

The immunohistochemical distribution of SP-D was compared with that of SP-A and KL-6 using a monoclonal antibody in lung tissues of 15 cases of collagen vascular disease-associated interstitial pneumonia (CVD-IP), 4 cases of hypersensitivity pneumonitis (CHP), and 6 cases of other diseases to determine their differences in distribution. In this study, the main targets were alveolar epithelial cells, especially those in the regenerating stage, as well as lymph vessels and stroma. The cytoplasm of type II alveolar epithelial cells and Clara cells was positive for SP-D, with sharp margins; interestingly, however, during the process of regeneration large positive cells were intermingled with relatively small negative cells, even in the same row of cells. In sharp contrast, staining for SP-A and KL-6 was positive in the cytoplasm of all the regenerating alveolar epithelial cells, as well as Clara cells. Staining for KL-6 was usually positive in the surface of air spaces in linear fashion. Staining for SP-A was also positive in elastic fibers in vascular walls. In areas of destruction of pulmonary structures, loose stroma and the endothelial cells of lymph vessels as well as their contents were distinctly positive for SP-A and/or KL-6 but not SP-D. Judging from these results in pulmonary tissues of CVD-IP and HP, SP-D might be a marker for maturity of regenerating epithelial cells. Both SP-A and KL-6 were detected in intimate relationship to the stage of regeneration of alveolar epithelial cells and were expressed before SP-D. In addition, the lymph vessels play a very important role in transfer of KL-6 into the bloodstream.

Differing distributions of CXCR3- and CCR4-positive cells among types of interstitial pneumonia associated with collagen vascular diseases.

Interstitial pneumonia (IP) is an important complication in collagen vascular diseases (CVDs). We examined the distribution of helper T cell subsets in lung biopsies of cases of IP associated with CVD (CVD-IP). The tissues from 27 CVD-IP patients with rheumatoid arthritis (RA), 8 with polymyositis or dermatomyositis (PM/DM), and 8 with systemic sclerosis (SSc) were compared with those from 10 patients with idiopathic pulmonary fibrosis (IPF) in our previous study. The expressions of CXCR3 and CCR4 (chemokine receptors associated in vitro with Th1 and Th2 cells, respectively) in the mononuclear infiltrate were analyzed immunohistochemically. The positive cells were semiquantified in fibrosing areas of the CVD-IP and IPF cases. The number of CXCR3-positive cells was significantly greater in RA-IP than in PM/DM-IP, SSc-IP, or IPF, whereas there were fewer CCR4-positive cells in RA-IP, PM/DM-IP, and SSc-IP than in IPF. The CXCR3-/CCR4-positive cells ratio was significantly higher in RA-IP and PM/DM-IP (but not in SSc-IP) than in IPF. These results support previous reports of the dominance of Th2 cells in some SSc-IP and IPF cases. However, Th1-type immune responses may predominate in RA-IP and PM/DM-IP. Our findings suggest that the pathogenesis of CVD-IPs differs with the helper T cell subset.

Expression of chemokine receptors CXCR3 and CCR4 in lymphocytes of idiopathic nonspecific interstitial pneumonia.

Little is known about the role of chemokines and their receptors interaction, which are essential for recruitment of selective lymphocyte subsets during inflammation, in the pathogenesis of idiopathic nonspecific interstitial pneumonia (NSIP). Recent studies have revealed Th1 and Th2 cells preferentially employ the chemokine receptors, CXCR3 and CCR4, respectively, in the process of accumulation into inflammatory sites. We evaluated the CXCR3 and CCR4 expression on infiltrated lymphocytes in lung tissues of 12 NSIP cases and 10 idiopathic pulmonary fibrosis (IPF) cases in our previous study. The number of CXCR3 positive lymphocytes of NSIP patients was significantly greater than that of IPF patients (261.1+/-145.1 vs. 64.9+/-27.0, P<0.01). The number of CCR4 positive lymphocytes of NSIP patients was significantly lower than that of IPF (9.5+/-8.3 vs.62.6+/-26.9, P<0.01). The CXCR3 to CCR4 ratio of NSIP patients was significantly greater than that of IPF patients (47.9+/-45.9 vs. 1.11+/-0.40, P<0.01). The differences of CXCR3 positive, CCR4 positive lymphocyte counts, and of CXCR3/CCR4 ratio between cellular and fibrosing NSIP were not significant. These results suggest that a Th1 pattern of chemokine receptor expression predominates in the lung interstitium of patients with NSIP but, in IPF patients, CCR4 might be relatively predominant, in contrast to the finding in NSIP patients, and that Th1/Th2 balance might be an important factor in the pathogenesis of NSIP.

Non-specific interstitial pneumonia; as the first clinical presentation of various collagen vascular disorders.

Recently, we have experienced significant numbers of patients diagnosed with non-specific interstitial pneumonia (NSIP) by open lung biopsy or video-assisted thoracoscopic surgery. The purpose of this work was to describe the clinical features of patients with collagen vascular disorders (CVD) presenting NSIP in the absence of systemic involvement. This study also involved a retrospective review of patients with CVD presenting clinical and pathological evidence of NSIP in the absence of systemic manifestations of CVD. We found seven patients (six from our experience and one from literature review) with histologically proven NSIP who later developed typical CVD more than 6 months after the first presentation of NSIP. In these cases, it was difficult to speculate the development of CVD at the point of first presentation. Therefore, association of CVD should be considered in patients with NSIP even in the absence of classical systemic involvement.

Idiopathic non-specific interstitial pneumonia: as an "autoimmune interstitial pneumonia".

Recently, we have experienced significant number of patients diagnosed with non-specific interstitial pneumonia (NSIP) by open lung biopsy or video-assisted thoracoscopic surgery. The purpose of this study is to compare clinical and pathological features of idiopathic NSIP and NSIP associated with underlying diseases (mainly autoimmune disorders). Forty-six patients with histologically proven NSIP were retrospectively collected. Twenty-four patients had underlying diseases (12 polymyositis/dermatomyositis, 5 systemic sclerosis, 2 rheumatoid arthritis, 2 Sjogren's syndrome, 1 ulcerative colitis, 1 primary biliary cirrhosis, and 1 multiple myeloma). Twenty-two of the 46 patients had no underlying diseases. It was very difficult to distinguish idiopathic NSIP and NSIP associated with underlying diseases, clinically and radiologically. Pathologically, Lymphocytic pneumonitis was demonstrated in both groups, and it was impossible to distinguish idiopathic NSIP and NSIP associated with underlying diseases. Since generalized symptoms were not observed in patients with idiopathic NSIP, and clinical and pathological features were identical to NSIP with several autoimmune disorders, we postulate new clinical entities of "autoimmune interstitial pneumonia" in cases without underlying diseases.

Distribution of CXCR3- or CCR4-positive cells in interstitial pneumonia associated with primary Sjogren's syndrome.

Patients with primary Sjogren's syndrome (SS) occasionally develop interstitial pneumonia (SS-IP), the prognosis of which is less grave compared with that of idiopathic pulmonary fibrosis (IPF). We examined distribution of helper T-cell subsets in open lung biopsy specimens from seven patients with SS-IP and, for comparison, ten patients with IPF. The expression of CXCR3 and CCR4, chemokine receptors associated in vitro with Th1 and Th2 cells, respectively, was analyzed in the mononuclear infiltrate using immunohistochemistry. The expression of CD4, CD8, and CD20 in the infiltrate was similarly examined. The positive cells were semiquantified in fibrosing areas and lymphoid clusters of both SS-IP and IPF. In fibrosing areas, CXCR3-positive cells were dominant over CCR4-positive cells in all cases of SS-IP, whereas the two types of cells showed no such difference in cases of IPF. Each of the CXCR3/CD4 and CXCR3/CCR4 ratios was significantly higher in SS-IP than in IPF ( P<0.05 and P<0.05, respectively). The CCR4/CD4 ratio showed a significantly lower value in SS-IP than in IPF ( P<0.05). In lymphoid clusters, prominent in SS-IP and few and small in IPF, CXCR3-positive cells predominated over CCR4-positive cells in both lung lesions. There was no significant difference of CXCR3/CCR4 ratio in lymphoid clusters between SS-IP and IPF ( P=0.33). These findings in SS-IP are in accordance with those reported in previous studies of the salivary glands of SS patients, where most of the infiltrating lymphocytes expressed CXCR3, and the expression of interferon-gamma was upregulated. In contrast, the Th2 cell dominance was reported in IPF in the previous studies. The present findings suggest that the pathogenesis of interstitial pneumonia is different between SS-IP and IPF in regard to the roles of helper T-cell subsets.

High molecular weight vimentin complex is formed after proteolytic digestion of vimentin by caspase-3: detection by sera of patients with interstitial pneumonia.

In a previous study, we demonstrated anti-vimentin antibodies in sera of patients with interstitial pneumonia. We hypothesized that antibodies in sera might detect vimentin fragments formed during the process of apoptosis. To prove this, recombinant human vimentin was digested by recombinant human caspase-3 or caspase-8. Then, Western blotting using several commercially available antibodies against human vimentin or patients' sera which had anti-vimentin autoantibodies, was performed. As a result, after recombinant human vimentin was digested by caspase-3 or caspase-8, several vimentin fragments were formed and detected by 2 kinds of monoclonal anti-vimentin antibodies (clone 3B4 and clone V9) as well as by polyclonal sheep anti-human vimentin antibody. It was demonstrated that high molecular weight vimentin was formed after the digestion of vimentin by caspase-3, which was only detected by patients' sera. The high molecular weight vimentin was not formed after digestion of vimentin by caspase-8. Our present results show that high molecular weight vimentin was formed after the digestion of vimentin by caspase-3. In addition, it is suggested that this high molecular weight vimentin acted as an autoantigen to form anti-vimentin autoantibody in vivo.

Regression of esophageal papillomatous polyposis caused by high-risk type human papilloma virus.

Esophageal squamous papilloma is an uncommon benign squamous epithelial polypoid tumor and is usually identified as a solitary lesion in the lower esophagus. Chronic mucosal irritation and infection with human papilloma virus (HPV) are two proposed etiologies. However, the natural history of esophageal squamous papilloma is unknown, and whether it can develop to esophageal cancer is also controversial. The authors report a case of esophageal papillomatous polyposis in which the presence of high-risk HPV DNA was proven by type-specific polymerase chain reaction (PCR). The patient was an 83-year-old man referred to our hospital with complaints of nausea and dysphagia. Esophago-gastroduodenoscopy (EGD) was carried out, and diffuse polyposis of the entire length of the esophagus and stenosis in the antrum of the stomach were revealed. Histological examination of the tissue confirmed the diagnosis of squamous papilloma of the esophagus and poorly differentiated adenocarcinoma of the stomach. Furthermore, HPV type-specific PCR was carried out in the biopsied specimens, and HPV type-16 and type-33 were detected. One month after total gastrectomy performed for the treatment of gastric cancer, follow-up EGD was carried out, and complete regression of the esophageal polyps was noted. This case is rare and supports the evidence that esophageal squamous papilloma is caused by infection with HPV. Furthermore, this case also reflects a unique aspect of the natural history of esophageal papillomatous polyposis.

Transforming growth factor beta1 gene polymorphism in patients with systemic sclerosis.

OBJECTIVE: To determine whether transforming growth factor beta1 (TGFbeta1) gene DNA polymorphism is associated with pathogenesis in the fibrosis of patients with systemic sclerosis (SSc). METHODS: Eighty-seven Japanese patients with SSc including 30 with diffuse type and 57 with limited type together with 110 unrelated controls were investigated. Pulmonary fibrosis was determined in 34 SSc patients using high-resolution chest computed tomography. TGFbeta1 genetic polymorphisms were analyzed in 2 loci; T869C (Leu10Pro) in codon 10 at exon 1, and C-509T in the promoter region using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). RESULTS: Neither the genotype of T/C polymorphism in T869C nor C/T polymorphism in C-509T revealed any difference in distribution between SSc and controls. In the group of SSc patients with pulmonary fibrosis, a weak but significantly high frequency (p = 0.05) of TC+CC (the presence of C allele) in T869C, and CT+TT (the presence of T allele) in C-509T was found. Compared with controls, the pulmonary fibrosis group showed no difference in the highly frequent alleles. CONCLUSION: Our results suggest that TGFbeta1 polymorphisms do not play a role in the pathogenesis of SSc, even though there remains the possibility of a risk factor for genetic susceptibility to pulmonary fibrosis.

Myofibroblasts proliferation of idiopathic and collagen vascular disorders associated nonspecific interstitial pneumonia.

Nonspecific interstitial pneumonia (NSIP) has been recognized as a separate histological classification of interstitial lung disease. Similar features are found not only in idiopathic NSIP, but also in NSIP associated with collagen vascular disorder (CVD-NSIP). We examined the clinical symptoms, laboratory findings, and prognosis of 13 cases of idiopathic NSIP and 11 cases of CVD-NSIP. Immunohistochemical staining was performed using the streptavidin/biotin/peroxidase method with anti-alpha-smooth muscle actin antibody. No differences in the distribution of clinical features, laboratory findings, and prognosis were observed between idiopathic NSIP and CVD-NSIP. In immunohistochemical staining of the fibrosing areas, myofibroblasts were observed in 7 of 13 idiopathic NSIP cases, but in 10 of 11 CVD-NSIP cases. With regards to intra-alveolar organization, myofibroblasts were observed in all 10 CVD-NSIP cases, but they were observed in only 2 of 9 idiopathic NSIP cases. We found a significantly higher myofibroblast proliferation in the intra-alveolar organization of CVD-NSIP compared to idiopathic NSIP. Clinically, idiopathic NSIP and CVD-NSIP are similar, but are pathologically different.

Immunohistochemical characterisation of pulmonary hyaline membrane in various types of interstitial pneumonia.

AIMS: Hyaline membrane (HM) in diffuse alveolar damage (DAD) pattern is frequently detected in the acute stage of interstitial pneumonia (IP). To determine the exact nature of HM, we investigated immunohistochemically 25 cases of HM-containing IP. METHODS: The cases examined using various kinds of antibodies were four cases associated with rheumatoid arthritis, five with usual interstitial pneumonia, two with dermatomyositis, five with viral infection, one case with progressive systemic sclerosis and eight cases caused by other agents. RESULTS: HM mostly reacted with antibodies to PE10 (SP-A), Factor VIII, KL-6 and EMA and, interestingly, stained for AE1/AE3, CK19, and Hup-1 in some cases, but was negative for PTAH staining. However, the immunoreactivities of HM varied even within the same disease or section. CONCLUSIONS: The immunohistochemical heterogeneity of HM suggests that HM may be formed by different mechanisms in various types of IP. Our findings also suggest that the main components of HM are derived from alveolar epithelial cells and their proteins, some including cytoplasmic element of CK19, and also from serum factors, but not fibrin. The immunohistochemical characteristics of HM in DAD pattern will aid understanding of the significance of HM formation in IP.

A study on intraalveolar exudates in acute mycoplasma pneumoniae infection.

Pathologic features of Mycoplasma pneumoniae infection (M. pneumonia) are generally non-specific, and the literature regarding the pathologic features of M. pneumonia with intraalveolar exudates is limited. Clinical and histopathological studies were performed in 3 patients with M. pneumonia which did not respond to erythromycin and minocycline, but all rapidly recovered after corticosteroid therapy. In pathologic findings, we observed intraalveolar exudates and focal organization in M. pneumonia, and its intraalveolar lesions were compared between M. pneumonia and bronchiolitis obliterans organizing pneumonia containing fibrin (BOOP). Immunohistochemical studies were performed using the streptavidin biotin peroxidase complex method with anti-alpha-smooth muscle actin antibody and anti-pancytokeratin AE1/AE3 antibody. In pathologic findings, more fibrin deposits in intaalveolar lesions were observed in M. pneumonia than in BOOP. In intaalveolar lesions of M. pneumonia, a larger amount of nuclear debris, more neutrophils, and more erythrocytes were noted. Myofibroblasts were observed in the organization of BOOP, while in the intaalveolar lesions of M. pneumonia, myofibroblasts were not observed. These results suggest that M. pneumonia with intraalveolar exudates responds well to corticosteroid and its intraalveolar lesions apparently differed from those in BOOP.

The distribution and number of Leu-7 (CD57) positive cells in lung tissue from patients with pulmonary fibrosis.

Leu-7 positive lymphocytes, including natural killer cells, play an important role in the immune system's surveillance function to prevent the development of cancer. The incidence of lung cancer is significantly high in patients with end-stage pulmonary fibrosis. We hypothesized that the number of Leu-7 positive cells may be decreased in areas of severe pulmonary fibrosis. To demonstrate this, Leu-7 positive cells were immunohistochemically stained in 41 lung specimens obtained from patients with idiopathic pulmonary fibrosis and pulmonary fibrosis associated with collagen vascular disorders. The number of Leu-7 positive cells was evaluated according to the pathological findings. In pathologically normal lung, Leu-7 positive cells were mostly found within the capillaries of the septa and rarely in the alveolar space or the stroma. The number of Leu-7 positive cells was 0.69 +/- 0.15 in areas of advanced fibrosis (n = 41), 2.39 +/- 0.60 in areas that had newly developeing fibrosis (n = 41), 1.14 +/- 0.57 in bronchiolitis obliterans organizing pneumonia (n = 9), and 1.35 +/- 0.87 in diffuse alveolar damage (DAD) (n = 11). The number of Leu-7 positive cells in areas of newly developing fibrosis (2.39 +/- 0.60) was significantly higher than that in areas of established fibrosis (0.69 +/- 0.15, P < 0.05). Our present study demonstrates a significant decrease in the number of Leu-7 positive cells in areas of advanced fibrosis. This evidence may partly explain the high incidence of lung cancer associated with pulmonary fibrosis.

[Adenocarcinoma of the lung with skeletal muscle metastasis, resulting in death due to myocardial metastasis: a case report].

A 57-year-old man was admitted to the hospital because of multiple subcutaneous masses with pain, mild dyspnea, and bloody sputum. He had been asymptomatic until one month earlier, when he began to have a dry cough and myalgia of the right forearm. A chest radiograph showed cardiomegaly. Whole-body computed tomographic scan, cytologic examination of the sputum, and histological examination of a subcutaneous nodule on the scalp resulted in the diagnosis of lung cancer with multiple organ metastases, including those to skeletal muscle and myocardium. Despite chemotherapy, he died suddenly on the 45th hospital day. Autopsy revealed that about half of the myocardium had been replaced by metastatic tumors, so we speculated that he died from heart failure due to cardiac muscle metastasis.

[Recurrence of thymoma accompanied with hypogammaglobulinemia 20 years after surgery: a case report].

We reported a case of recurrence of localized thymoma accompanied with hypogammaglobulinemia (Good's syndrome) 20 years after surgery. A 74-year-old man was admitted to this hospital because of mediastinal tumor and chronic pulmonary infection. He had been thymectomised at the age of 55 because of spindle cell thymoma. After that, he had been asymptomatic until January 1997, when he began to have a recurrent productive cough, and low-grade fever. Laboratory findings revealed hypogammaglobulinemia. Percutaneous needle biopsy of the mediastinal tumor revealed spindle cell thymoma. Therefore, hypogammaglobulinemia with thymoma (Good's syndrome) accompanied with a chronic lower respiratory tract infection was diagnosed. Immunologic studies revealed a marked decrease of CD 20 positive cells and decreased lymphocyte activation under the stimuli of phytohemagglutinin and concanavalin A. The thymoma was resected in Dec 1997, but the serum immunoglobulin showed no increase at al.

[Successful use of immunosuppressive agents for the treatment of progressive rheumatoid interstitial lung disease: a case report].

Interstitial pneumonia (IP) is sometimes a fatal complication of rheumatoid arthritis (RA). We describe a patient with progressive rheumatoid interstitial pneumonia, who responded to intravenous intermittent cyclophosphamide (IV-CY) and cyclosporine (CsA). A 62-year-old man with rheumatoid arthritis was admitted to this hospital because of dyspnea. Examinations on admission revealed that he had active RA with vasculitis and IP Initially, he responded to high-dose corticosteroid therapy. A lung biopsy performed after initial corticosteroid therapy revealed diffuse interstitial pneumonia with marked infiltrations of macrophages into the air spaces. On corticosteroid therapy with prednisolone 30 mg/day, the IP became exacerbated and was refractory to the current high-dose steroid treatment. He responded to intravenous cyclophosphamide, but his IP remained unstable. After CsA treatment was started, a clinical remission was obtained. In this case, CsA was the most effective agent tried. Clinical and pathological considerations led us to speculate that activated alveolar macrophages played a crucial role in the pathogenesis of steroid-resistant IP in this patient, and that the clinical remission induced by CsA may have been due to its inhibitory effect on alveolar macrophages.