A case series describing common radiographic and pathologic patterns of hard metal pneumoconiosis.

INTRODUCTION: Hard metal pneumoconiosis is a rare but serious disease of the lungs associated with inhalational exposure to tungsten or cobalt dust. Little is known about the radiologic and pathologic characteristics of this disease and the efficacy of treating with immunosuppression. OBJECTIVE: We describe the largest cohort of patients with hard metal pneumoconiosis in the literature, including radiographic and pathologic patterns as well as treatment options. METHODS: We retrospectively identified patients from the University of Pittsburgh pathology registry between the years of 1985 and 2016. Experts in chest radiology and pulmonary pathology reviewed the cases for radiologic and pathologic patterns. RESULTS: We identified 23 patients with a pathologic pattern of hard metal pneumoconiosis. The most common radiographic findings were ground glass opacities (93%) and small nodules (64%). Of 20 surgical biopsies, 17 (85%) showed features of giant cell interstitial pneumonia. Most patients received systemic corticosteroids and/or steroid-sparing immunosuppression. CONCLUSIONS: Hard metal pneumoconiosis is characterized predominately by radiographic ground glass opacities and giant cell interstitial pneumonia on histopathology. Systemic corticosteroids and steroid-sparing immunosuppression are common treatment options.

Proteasome Inhibitor Carfilzomib-Based Therapy for Antibody-Mediated Rejection of the Pulmonary Allograft: Use and Short-Term Findings.

We present this observational study of lung transplant recipients (LTR) treated with carfilzomib (CFZ)-based therapy for antibody-mediated rejection (AMR) of the lung. Patients were considered responders to CFZ if complement-1q (C1q)-fixing ability of their immunodominant (ID) donor-specific anti-human leukocyte antibody (DSA) was suppressed after treatment. Treatment consisted of CFZ plus plasma exchange and immunoglobulins. Fourteen LTRs underwent CFZ for 20 ID DSA AMR. Ten (71.4%) of LTRs responded to CFZ. DSA IgG mean fluorescence intensity (MFI) fell from 7664 (IQR 3230-11 874) to 1878 (653-7791) after therapy (p = 0.001) and to 1400 (850-8287) 2 weeks later (p = 0.001). DSA C1q MFI fell from 3596 (IQR 714-14 405) to <30 after therapy (p = 0.01) and <30 2 weeks later (p = 0.02). Forced expiratory volume in 1s ( FEV1 ) fell from mean 2.11 L pre-AMR to 1.92 L at AMR (p = 0.04). FEV1 was unchanged after CFZ (1.91 L) and subsequently rose to a maximum of 2.13 L (p = 0.01). Mean forced expiratory flow during mid forced vital capacity (25-75) (FEF25-75 ) fell from mean 2.5 L pre-AMR to 1.95 L at AMR (p = 0.01). FEF25-75 rose after CFZ to 2.54 L and reached a maximum of 2.91 L (p = 0.01). Responders had less chronic lung allograft dysfunction or progression versus nonresponders (25% vs. 83%, p = 0.04). No deaths occurred within 120 days and 7 patients died post CFZ therapy of allograft failure. Larger prospective interventional studies are needed to further describe the benefit of CFZ-based therapy for pulmonary AMR.

Approach to a lung transplant biopsy.

With increasing numbers of lung transplants being performed worldwide, lung transplant allograft biopsies are becoming increasingly common. The evaluation of lung transplant biopsies typically focuses on the assessment of allograft rejection and infection, but other entities may also be seen in biopsy material. Presented here is an approach to lung transplant biopsies, in which there is an overview major diagnostic entities that may be encountered and discussion of findings that may present interpretive challenges.

C4d deposition in lung allografts is associated with circulating anti-HLA alloantibody.

UNLABELLED: The complement activation demonstrated by vascular C4d deposition is used to diagnose antibody-mediated rejection (AMR) in renal allografts, but remains controversial in lung transplantation (LTX). METHODS: C4d deposition was assessed by immunohistochemistry in 192 lung transplant biopsies from 32 patients. ELISA analysis was performed on 415 serum samples in those 32 temporally and rejection-grade matched LTX patients; 16 patients developed HLA-Ab, while the other 16 patients remained negative. The specificity of C4d staining was further compared in 18 additional LTX patients without HLA-Ab or acute cellular rejection (ACR), but in the presence of CMV-pneumonitis or reperfusion injury. RESULTS: Specific subendothelial C4d deposition was seen in 5 of 16 (31%) patients with HLA-Ab and was absent in 16 patients without HLA-Ab (p<0.05). All patients with specific C4d deposition exhibited donor-specific HLA-Ab. There were 13 patients with bronchiolitis obliterans syndrome in the group of 16 HLA-Ab positive patients, versus 2/16 in ELISA-negative patients (p<0.005). One of 7 patients with CMV pneumonitis and 2 of 11 patients with reperfusion injury also showed C4d positivity (not statistically significant). CONCLUSIONS: In this study, specific subendothelial C4d deposition was a marker for the involvement of HLA-Ab in lung allograft rejection. The patchy nature, low sensitivity, and specificity of C4d staining might limit clinical use in protocol biopsies. However, in patients with decreasing pulmonary function, refractory ACR and/or HLA-Ab, specific C4d deposition may serve as a marker of coexistent AMR.

Phase I study of gemcitabine given weekly as a short infusion for non-small cell lung cancer: results and possible immune system-related mechanisms.

PURPOSE: To define the maximum tolerated dose (MTD) and the nature of the toxicities associated with gemcitabine given as a short infusion to patients with non-small cell lung cancer (NSCLC). Secondary objectives were to monitor immunologic response, clinical response, and survival. PATIENTS AND METHODS: Thirty-two patients diagnosed with advanced inoperable NSCLC and performance status of 0 or 1 participated in this study. Patients consisted of 22 males and 10 females whose median age was 62 years (range 32-79). Gemcitabine was administered as a 30 min infusion once weekly for 3 weeks followed by 1 week of rest. Patients were enrolled at six gemcitabine dose levels ranging from 1000 to 3500 mg/m2. Patients completed a median of four cycles (range 1-17). Responses were evaluated after every two cycles. RESULTS: Toxicity was evaluated in all 32 patients. The MTD was not reached as gemcitabine was well tolerated at all dose levels. Grade 4 toxicity occurred in three (9%) patients: pulmonary and lymphocytopenia in one patient each, and both neurocortical and cardiac in one patient. Grade 3 toxicity was found in a total of 20 (63%) patients: pulmonary in 10 (31%) patients; pain in 6 (19%) patients; liver toxicity in 6 (19%) patients; leukopenia and lymphocytopenia in 5 (16%) patients each; anemia, nausea, and cardiac toxicity in 3 (9%) patients each; proteinuria and infection in 2 (6%) patients each; and hemorrhage in 1 (3%) patient. Of the 29 patients evaluable for response, seven objective responses were achieved: six at the 2200 mg/m2 dose level and one at the 2800 mg/m2 dose level. The distribution of responses differed significantly by dose (P = 0.0124 by the exact chi-square test for independence). The overall response rate was 24.1% (95% CI, 10.3-43.5%). At 6 h post-infusion, there was a significant increase in spontaneous tumor necrosis factor (TNF) release and stimulated interleukin (IL)-2 production, and significant decreases in total white blood cell and lymphocyte counts (CD3+, CD8+, and CD16+ lymphocytes) and resting and stimulated superoxide production by formyl-methionyl-leucyl-phenylalanine (fMLP), phorbol myristate acetate, and opsonized zymosan (OPS-Z). At 24 h post-infusion, there were significant decreases in total lymphocyte count, lymphocyte subsets (CD3+, CD4-, CD8+, CD56+, CD19+), and in resting and stimulated superoxide production by fMLP and OPS-Z. There also appeared to be an association between the levels of spontaneous TNF release and the severity of both gastrointestinal (GI) and pulmonary toxicities. CONCLUSION: Gemcitabine given as a short infusion was well tolerated at the dose levels of 1000-3500 mg/m2. The MTD was not reached. Toxicities appeared to be cumulative with multiple cycles. Gemcitabine appears to have activity against NSCLC. Although there was a differential dose-response rate among dose levels, increasing the gemcitabine dose beyond 2200mg/m2 did not show increased clinical response. Gemcitabine appears to modulate the immune response, which may in turn mediate both response and toxicity, although no statistically significant correlation between immune and clinical response was detected.

Genotypic analysis of pulmonary Langerhans cell histiocytosis.

Reported studies show that the systemic form of Langerhans cell histiocytosis (LCH) is a clonal expansion of Langerhans cells (LC) associated with aberrant expression of several oncogenes or tumor-suppressor genes. LCH of the lung is a heterogenous group of lesions thought to be a reactive rather than neoplastic process. The histogenesis of the LCH of the lung is uncertain, and to date there are no studies investigating its underlying molecular abnormalities. We performed comparative genotypic analysis by using allelic loss (LOH) of polymorphic microsatellite markers associated with tumor suppressor genes. Fourteen cases of formalin-fixed, paraffin-embedded LCH of the lung were studied. Microdissection of a total of 26 nodules from 14 patients and paired reference lung tissue was performed under stereomicroscopic visualization. To evaluate allelic loss, we used a panel of 11 polymorphic microsatellite markers that were situated at or near tumor suppressor genes on chromosomes 1p, 1q, 3p, 5p, 9p, 17p, and 22q. The PCR products were analyzed by using capillary electrophoresis to identify germline heterozygous alleles and LOH. Allelic loss at 1 or more tumor suppressor gene loci was identified in 19 of 24 nodules. The total fractional allelic loss (FAL) ranged from 6% (1q) to 41% (22q), with a mean of 22%. The FAL in individual cases ranged from 0 (7 nodules) to 57% (1 nodule). Fifteen discordant allelic losses at 1 to 3 chromosomal loci were identified in 8 patients with multiple synchronous nodules. Our results show that LOH of tumor suppressor genes is present in the LCH of the lung, and they indicate that the putative tumor suppressor genes situated on chromosomes 9p and 22q may play a role in the development of a subset of the LCH of the lung.

Absence of jaagsiekte sheep retrovirus DNA and RNA in bronchioloalveolar and conventional human pulmonary adenocarcinoma by PCR and RT-PCR analysis.

Bronchioloalveolar adenocarcinoma (BAC) morphologically resembles sheep pulmonary adenomatosis (SPA), a contagious ovine pulmonary adenocarcinoma caused by the jaagsiekte sheep retrovirus (JSRV). Previously, positivity for JSRV by immunostaining, reverse-transcription polymerase chain reaction (RT-PCR), and Western blot was reported in most nonmucinous BACs. Our objective in this study was to analyze additional BAC subtypes and conventional adenocarcinomas (CA) to further substantiate this association. Tumor tissue was microdissected from unstained paraffin sections of 26 cases of formalin-fixed, paraffin-embedded BAC (7 mucinous, 17 nonmucinous, 2 sclerosing) and 29 cases of CA. Positive controls consisted of 2 separate paraffin blocks of known SPA. Primer sequences were derived that were capable of hybridizing to all reported strain variants of both the DNA (endogenous) and RNA (exogenous) forms of JSRV. Each sample was tested using both PCR (DNA) and RT-PCR (RNA). All BAC and CA cases were negative for JSRV. Positive controls yielded PCR products that were sequenced and precisely matched the published prototype stain of JSRV. To control for negative effects of tissue fixation, dilutions of positive control tissue were added to BAC and CA samples. Detection of JSRV was evident at 1:50 dilution. Although the possibility of a viral association with BAC cannot be excluded, this study shows that the association with JSRV is probably very weak, if present at all.

Pulmonary Langerhans' cell histiocytosis: molecular analysis of clonality.

Pulmonary Langerhans' cell histiocytosis (LCH) is a form of Langerhans' cell disease that primarily affects smokers in the third to fifth decade. Extrapulmonary manifestations are rare. Its clinical course is typically characterized by stabilization or regression of bilateral micronodular infiltrates seen on chest radiographs; progression to honeycomb fibrosis is rare. Because the clinical course of pulmonary LCH is distinct from systemic multiorgan LCH, currently thought to be a clonal proliferative disorder, we examined the X-linked polymorphic human androgen receptor assay (HUMARA) locus to assess clonality in female patients with one or more discrete LCH cell nodules in open lung biopsies. Langerhans' cells (LCH cells) were excised from formalin-fixed, paraffin-embedded tissue by microdissection to assure a relatively pure cellular population, and studies for differential methylation patterns at the HUMARA locus were performed. Twenty-four nodules in 13 patients were evaluated. Seven (29%) were clonal and 17 (71%) were nonclonal. Of six cases with multiple discrete nodules, three (50%) showed a nonclonal LCH cell population. In one biopsy with five nodules, two nodules were clonal with one allele inactivated, one nodule was clonal with the other allele inactivated, and two nodules were nonclonal. In contrast to systemic LCH, pulmonary LCH appears to be primarily a reactive process in which nonlethal, nonmalignant clonal evolution of LCH cells may arise in the setting of nonclonal LCH cell hyperplasia. Cigarette smoking may be the stimulus for pulmonary LCH in contrast to other forms of LCH.

Pulmonary apical cap: a distinctive but poorly recognized lesion in pulmonary surgical pathology.

Thirteen cases of pulmonary apical cap (PAC), resected for the exclusion of a clinical diagnosis of lung carcinoma, were reviewed, and their distinctive morphology was described. PAC occurred in older individuals, particularly in the apices of the upper lobes, and by radiographic examination appeared as spiculated subpleural masses ranging from 0.7 to 5.2 cm in diameter. Microscopically, these subpleural scars were pyramid shaped with overlying pleural adhesions and hyaline pleural plaques. They were characterized by a dense basophilic fibrosis of the pulmonary parenchyma with air spaces filled with old, mature collagen and the underlying elastic skeleton contracted in an accordion-like fashion with reduplicated curls of elastic fibers. Scar emphysema was prominent at the periphery of these fibrous nodules. PAC should be recognized for its unique histology because its appearance in the surgical pathology laboratory will likely increase in incidence with the evolution of more sensitive pulmonary radiographic studies. A chronic ischemic etiology is favored.

Involvement of 2p23 in pulmonary inflammatory pseudotumors.

Pulmonary inflammatory pseudotumors (IP) are rare mesenchymal proliferations that have a polymorphic histology and an unpredictable biologic behavior. The histologic spectrum of IP has led to uncertainty as to whether this tumor has a reactive or neoplastic pathogenesis. Reports of extrapulmonary IP have identified clonal chromosomal aberrations involving 2p23 in the region of the ALK gene. Using fluorescence in situ hybridization with a probe flanking the ALK gene at 2p23 and immunostaining for the ALK gene product, we studied formalin-fixed, paraffin-embedded tissues of pulmonary IP and found a subset (33%) with 2p23 aberrations. We suggest that chromosomal rearrangements and ALK immunostaining may be helpful in the diagnosis of a group of pulmonary IP and should be investigated as a potential tool for predicting their future biologic behavior. An association with anaplastic large-cell lymphoma was also observed. HUM PATHOL 32:428-433.

Nodular amyloidoma and primary pulmonary lymphoma with amyloid production: a differential diagnostic problem.

Nodular amyloidomas (NA) of the lung are non-neoplastic inflammatory nodules containing eosinophilic amyloid deposits and a lymphoplasmacytic infiltrate. In some instances, the extensive amyloid deposits may obscure an underlying lymphoproliferative disorder. The histologic and immunohistologic features that discriminate these two differential diagnostic possibilities were studied in this series of six cases of NA and five cases of primary low-grade malignant lymphomas of lung with secondary amyloid deposits (ML). Two of lymphoma cases showed histopathologic and immunophenotypic features of B-cell chronic lymphocytic leukemia/small lymphocytic lymphoma (B-cell CLL/SLL), and three cases were low-grade B-cell lymphoma derived from mucosa associated lymphoid tissue (MALT lymphoma). Key discriminating morphologic features between NA and ML included lymphatic tracking of the cellular infiltrate (3/5 ML; 1/6 NA), pleural infiltration (3/5 ML; 0/6 NA), sheet-like masses of plasma cells (5/5 ML; 0/6 NA) and reactive follicles (4/5 ML; 1/6 NA). Lesional circumscription, vascular and bronchial destruction, lymphoepithelial lesions, and granulomas were not helpful discriminators. Immunohistochemical features indicating a dominant CD20+, CD79a+ B-cell population (5/5 ML; 0/6 NA), light chain restriction (4/5 ML; 0/6 NA), and aberrant antigen expression of CD20/CD43 (2/5 ML; 0/6 NA) were helpful. Amyloid tumors with a reactive lymphoplasmacytic infiltrate can be separated from low-grade malignant lymphomas utilizing both histologic and immunohistochemical features.

The anatomic distribution of acute cellular rejection in the allograft lung.

BACKGROUND: Transbronchial lung biopsy (TBLB) is used for routine monitoring and diagnosing of acute cellular rejection (ACR) in the lung allograft, and yet the optimal anatomic site for lung biopsy has not been investigated. We examined our clinical data to clarify the distribution of ACR in the lung allograft monitored by TBLB. METHODS: A retrospective case-series study was done reviewing the pathology files and slides of TBLB performed on lung allograft recipients. In 73 patients, transbronchial biopsies were taken from more than one lobe. RESULTS: Identical grades of ACR were seen in 33 of 73 (45%) patients, and a single-grade difference in ACR was noted 34 of 73 (47%) patients. Six cases demonstrated two or more grade differences on biopsies taken from two separate lobes. Among cases with different grades of ACR, the "upper" lobes had a higher grade in 35% (14/40) and the "lower" lobes had a higher grade in 65% (26/40). CONCLUSIONS: If limitations on the site for transbronchial biopsy exist, biopsies of the lower lobes appear more informative.

Segmental nonanastomotic bronchial stenosis after lung transplantation.

BACKGROUND: Nonanastomotic distal bronchial stenosis has been observed in some patients after lung transplantation. We investigated its relationship with acute cellular rejection (ACR), infection, and ischemia. METHODS: Between January 1994 and December 1997, 246 lung transplantations were performed at our hospital. These cases were retrospectively reviewed and evaluated to identify those patients with nonanastomotic bronchial stenosis. RESULTS: Six patients had bronchial stenosis within the grafted airway distal to the uninvolved anastomotic site. The average ACR before stenosis was 1.9 compared with 1.6 in a control group. ACR at the time of first recognition of the stenosis ranged from A2 to A3.5, with an average value of A2.9. All 6 patients demonstrated alloreactive airway inflammation before and at the time of stenosis. Four patients had evidence of ischemic damage in the perioperative period. CONCLUSIONS: Segmental nonanastomotic large airway stenosis after lung transplantation should be assessed separately from anastomotic complications. Although the pathogenesis is unclear, certainly one should consider alloreactive injury, ischemic damage, and infection as individual and coercive causes.

Eosinophilic pneumonia-like areas in idiopathic usual interstitial pneumonia.

Usual interstitial pneumonia is the most common idiopathic chronic interstitial pneumonia, characterized by a temporally heterogenous pattern of interstitial injury with interstitial mononuclear infiltrates, septal fibromyxoid nodules, and parenchymal scarring. This report details the presence of focal eosinophilic pneumonia in six cases of usual interstitial pneumonia in the absence of known causes of this reaction. The relationship of eosinophilic infiltrates in usual interstitial pneumonia with regard to pathogenesis, differential diagnosis, and prognosis is discussed.

11q13 allelic imbalance discriminates pulmonary carcinoids from tumorlets. A microdissection-based genotyping approach useful in clinical practice.

Pulmonary tumorlets are minute neuroendocrine cell proliferations believed to be precursor lesions to pulmonary carcinoids. Little is known of their molecular pathogenesis because of their small size. Using tissue microdissection, we evaluated 11q13 region allelic imbalance in the pathogenesis of pulmonary tumorlet/carcinoid lesions. The int-2 gene was selected because of its chromosomal location at 11q13 in close proximity to MEN1, a tumor suppressor gene frequently mutated in familial forms of neuroendocrine cancer. Three cohorts of patients were studied: subjects with typical carcinoid tumors and coexisting tumorlets (n = 5), typical carcinoids without tumorlets (n = 6), and tumorlets alone without carcinoid lesions (n = 5). A total of 11 carcinoids and 11 tumorlets were microdissected from 4-micrometer-thick histological sections. Genotyping was designed to detect allelic imbalance of the int-2 gene and involved DNA sequencing of two closely spaced deoxynucleotide polymorphisms. Subjects shown to be informative were evaluated for allelic imbalance in tumorlet/carcinoid tissue. Eight of 11 (73%) carcinoids manifested allelic, in contrast to only one of 11 (9%) of tumorlets. Int-2 allelic imbalance was significantly associated with carcinoid tumor formation (P < 0.01). In patients having both carcinoid tumors and tumorlets, the latter showed allelic balance and were thus discordant in genotype with coexisting carcinoid excluding pathogenesis of tumorlets from intramucosal spread from carcinoid tumors. Int-2 allelic imbalance was shown to be an early event in carcinoid tumor formation by virtue of the absence of allelic imbalance for other common cancer-related gene disturbances involving 11p13 (Wilms' tumor), 3p25 (von-Hippel-Lindau), and 17p13 (p53). Demonstration of 11q13 allelic imbalance by microdissection/genotyping may be a useful discriminatory marker for pulmonary neuroendocrine neoplasia.

The significance of bronchus-associated lymphoid tissue in human lung transplantation: is there an association with acute and chronic rejection?

BACKGROUND: In animal models of acute rejection in lung allografts, bronchus-associated lymphoid tissue (BALT) plays a major role in the induction and persistence of the alloreactive response. We undertook a study of the clinical and histologic associations with BALT identified on transbronchial biopsy in human lung allograft recipients. METHODS: Transbronchial biopsies of patients receiving single lung, double lung, and combined heart-lung transplantation from 1984 to 1997 at the University of Pittsburgh Medical Center were reviewed. Seventy-seven patients had transbronchial biopsies demonstrating BALT. We examined all pathologic reports and slides, and graded rejection utilizing the Revised Working Formulation for the Classification of Pulmonary Allograft Rejection. Twenty-nine of 77 patients were selected at random to evaluate the distribution of BALT lymphocyte subsets immunohistochemically. RESULTS: There was no relationship between native disease or the transplant procedure and the identification of BALT. BALT was found from 9 days to 2431 days after transplant (average: 440 days; median: 157 days) in association with clinically insignificant acute cellular rejection (A0, A1) in 75% of cases. Bronchiolitis obliterans developed in 29% of patients with a BALT-positive biopsy, a percentage not different from that of our overall lung transplant population. Immunohistochemical examination of BALT showed helper T cells predominated over cytotoxic T cells in zones surrounding B cell-rich follicular center cells. CONCLUSIONS: The association of BALT with high-grade acute cellular rejection and with the development of bronchiolitis obliterans could not be confirmed in human lung allografts. BALT most often accompanied A0 or A1 rejection. This raises the possibility that the presence of BALT on transbronchial biopsy may be part of the evolution of immunologic tolerance in human pulmonary allografts.

Mixed hematopoietic chimerism induces donor-specific tolerance for lung allografts in rodents.

Mixed hematopoietic chimerism is a state in which bone marrow hematopoietic stem cells from two genetically different animals coexist. We investigated whether mixed hematopoietic chimerism, resulting from the transplantation of host and donor bone marrow into a lethally irradiated rat, would confer donor-specific tolerance to lung allografts. Recipient rats (Fisher or or Wistar Furth [WF]) were irradiated (1,100 cGy) and reconstituted with a mixture of T-cell-depleted syngeneic plus allogeneic bone marrow. After mixed chimerism was documented by the presence of donor- and host-derived cells in the peripheral blood 4 wk after bone marrow reconstitution, mixed chimeras underwent orthotopic left lung transplantation with donor-specific and third-party lung allografts. No immunosuppressive agents were administered after lung transplantation. All donor-specific lung allografts were accepted by mixed chimeras (n = 40), while all third-party grafts (n = 7) were rejected within 10 d, a time course similar to that for grafts transplanted into naive recipients (n = 14). Radiation control recipients (n = 7) who did not develop mixed chimerism because the donor bone marrow had failed to engraft, also rejected donor-specific grafts within 10 d. We conclude that mixed hematopoietic chimerism induces donor-specific transplantation tolerance to lung allografts.

Erdheim-Chester disease: clinical, radiologic, and histopathologic findings in five patients with interstitial lung disease.

Erdheim-Chester disease is a clinicopathologic entity defined by a characteristic pattern of symmetric osteosclerosis caused by an infiltrate of mononuclear cells that include prominent numbers of foamy histiocytes. About half of patients have extraskeletal manifestations, including involvement of the hypothalamus/posterior pituitary, orbit, retroperitoneum, skin, lung, and heart. Pulmonary involvement is an uncommon but important manifestation of Erdheim-Chester disease because it causes significant morbidity and mortality. A review of the Mayo Clinic files produced four patients with confirmed Erdheim-Chester disease in whom lung biopsy had been performed. One additional patient was included from the University of Pittsburgh. Four patients were women. The mean age was 53.6 years (range 25-70 years). All patients had bilateral and symmetric sclerotic bone lesions characteristic of Erdheim-Chester disease, although in three the skeletal abnormalities were discovered only after lung biopsy. Four patients had dyspnea, and one also had a dry cough. One patient died 17 months after diagnosis. Chest radiographs showed diffuse interstitial infiltrates in all patients, with an upper zone predominance in three. Thoracic computed tomography (CT) scans showed thickening of the visceral pleura and interlobular septa with patchy associated fine reticular and centrilobular opacities and ground glass attenuation. Lung biopsy specimens showed an infiltrate of foamy histiocytes, lymphocytes, and scattered Touton giant cells with associated fibrosis in a striking lymphatic distribution. The infiltrate involved visceral pleura, interlobular septa, and bronchovascular bundles. Immunohistochemical stains were positive for CD68 in all cases and S-100 protein in four cases. Stains for CD1a were consistently negative. Ultrastructural studies in one case showed no Birbeck granules. Although in bone the histologic features of Erdheim-Chester disease may overlap with Langerhans' cell histiocytosis, its expression in the lung is distinct. Lung involvement in Erdheim-Chester disease has emerged as a unique radiographic and histologic entity.

Bronchioloalveolar adenocarcinoma of lung: monoclonal origin for multifocal disease.

In an attempt to understand the histogenesis and molecular pathogenesis of multifocal bronchioloalveolar lung carcinoma (BAC) we studied 28 cases of BAC using a topographic genotyping approach for the presence of K-ras exon 1 mutations and p53 loss of heterozygosity (LOH). This analytical approach demonstrated K-ras exon 1 mutations in 12.5% of solitary BACs, 40% of BACs with microscopic or macroscopic satellite lesions, and 60% of BACs with intrathoracic metastases. In all cases with K-ras mutations, the identical point mutation was present in the primary, satellite, and intrathoracic metastatic lesions. When p53 LOH was demonstrated in the primary lesion, it was also detected in the satellites and intrathoracic metastases. No significant association was noted between the presence of K-ras mutations and p53 LOH. The results strongly support a monoclonal origin of multifocal BACs. Furthermore, the findings support the theories explaining the origin of multifocal BAC by intraalveolar route of spread, intrapulmonary lymphatic spread, or aerosolization leading to implantation at different sites. A trend toward an increased frequency of K-ras mutations and p53 LOH in BACs with satellites or metastases compared to solitary BACs was noted.