Pulmonary alveolar proteinosis (PAP) is a rare condition in which pulmonary macrophages fail to clear surfactant, resulting in the alveolar accumulation of lipoproteinaceous debris. The histopathology of PAP is typified by diffuse filling of terminal airways with eosinophilic, PAS/diastase (PAS/D)‐positive acellular material. We present five patients who showed histopathological changes in the lungs consistent with mild PAP. However, these cases were notable for the abundance of degenerating alveolar macrophages, weak PAS staining of lipoproteinaceous material and paucity of lamellated bodies on ultrastructural examination. Only one patient showed the CT finding of mosaiform ‘crazy‐paving’ and the opalescent bronchoalveolar lavage fluid characteristic of PAP. In one case, therapeutic lung lavage based on a presumptive diagnosis of PAP exacerbated respiratory distress. Three patients showed partial or near‐complete resolution of disease in response to high‐dose corticosteroid therapy, a treatment approach that is generally ineffective in PAP. We conclude that distinguishing ‘variant alveolar lipoproteinosis’ from classical PAP is clinically important. Despite the otherwise typical appearance of lipoproteinaceous alveolar material in lung biopsies, the presence of degenerating foamy macrophages and atypical histochemical, ultrastructural and radiographic features suggest a steroid‐responsive form of proteinosis that is likely pathogenetically distinct and may not be amenable to whole‐lung lavage.

The prospect of establishing serum metabolomic profiles offers great clinical significance for its potential to detect human lung cancers at clinically asymptomatic stages. Patients with suspicious serum metabolomic profiles may undergo advanced radiological tests that are too expensive to be employed as screening tools for the mass population. As the first step to establishing such profiles, this study investigates correlations between tissue and serum metabolomic profiles for squamous cell carcinoma (SCC) and adenocarcinoma (AC) in the lungs of humans. Tissue and serum paired samples from 14 patients (five SCCs and nine ACs), and seven serum samples from healthy controls were analyzed with high-resolution magic angle spinning proton magnetic resonance spectroscopy (HRMAS (1)HMRS). Tissue samples were subjected to quantitative histological pathology analyses after MRS. Based on pathology results, tissue metabolomic profiles for the evaluated cancer types were established using principal component and canonical analyses on measurable metabolites. The parameters used to construct tissue cancer profiles were then tested with serum spectroscopic results for their ability to differentiate between cancer types and identify cancer from controls. In addition, serum spectroscopic results were also analyzed independent of tissue data. Our results strongly indicate the potential of serum MR spectroscopy to achieve the task of differentiating between the tested human lung cancer types and from controls.

The multiplicity of epithelioid and mesenchymal forms of diffuse malignant mesothelioma includes patterns that may mimic another process. Identification of the multiplicity of patterns may help in the diagnosis of diffuse malignant mesothelioma. One pattern that has not been described is lymphangiomatoid. We observed six cases with ovoid or elongated or irregular anastomosing vascular-like spaces lined by flattened cells simulating lymphangioma. The luminal spaces could contain proteinaceous material simulating lymph but not erythrocytes. The cells lining the spaces were mesothelial by immunohistochemical staining. The lymphangiomatoid areas never constituted more than 40% of the area of the tumor on the slides. When seen in more solid areas of tumor, the lymphangiomatoid structures generally did not produce diagnostic difficulty. However, when seen at the edge of solid tumor or forming an irregular nodule or invading into adjacent adipose tissue, these lymphangiomatoid structures could be confusing. All six patients had been exposed to asbestos either by occupation or by spousal exposure. Three patients received chemotherapy. One patient died of diffuse malignant mesothelioma of the pleura.

Tracheal stenosis in adults usually is the result of mechanical injuries either from direct trauma or intubation. Rarely do cases develop in patients without such a precedent history, and there are few reports of the pathology of idiopathic tracheal stenosis (ITS). We reviewed clinicopathologically, 63 tracheal resections for tracheal stenosis in patients who had no antecedent explanation for their stenosis. We contrasted these 63 cases with 34 cases of tracheal stenosis owing to chondromalacia (CM) after mechanical injury. All 63 cases occurred in females, with a mean age of 49 years. The most common symptom was dyspnea on exertion. The average duration of symptoms was greater than 2 years. One-third of the patients gave a history of gastroesophageal reflux. All but one of the cases occurred in the subglottic region and/or upper one-third of the trachea. Pathologically, most cases showed extensive keloidal fibrosis and dilation of mucus glands, a finding that was not obvious in most cases of CM. ITS has relatively normal cartilage with smooth inner and outer perichondrium, whereas CM has extensive degeneration of cartilage with irregular border of inner perichondrium observable at shirt sleeve magnification. Immunohistochemical staining for estrogen receptor and progesterone receptor was positive in fibroblasts cells in most cases. ITS is a rare disease and restricted to females. It may represent some form of fibromatosis. ITS can be distinguished histologically from CM in tracheal resection specimens in most cases.

The World Health Organization classification applies the term “pulmonary inflammatory myofibroblastic tumor” to a histologically variegate set of pulmonary inflammatory pseudotumors. However, often these lesions bear little resemblance to tumors of myofibroblastic origin. To elucidate histogenesis, we examined 18 cases from our institution files. The cases were stained with antibodies to smooth muscle actin (SMA), Factor XIIIa, CD3, CD20, CD68, S-100, anaplastic lymphoma kinase (ALK-1), and human herpevirus-8 (HHV-8). The percentage of positive-staining cells within a defined tumor area (400,000 μm2) was determined by light microscopy and morphometric analysis. Ten cases (56%) showed myofibroblastic differentiation, as judged by positive SMA staining of spindle cells. All cases showed substantial numbers of CD68+, Factor XIIIa+, and S-100+ monocytoid cells. Fifty percent were ALK-1+, and one was HHV-8+. We conclude that the term “inflammatory myofibroblastic tumor” is a misnomer, as nearly half of cases show no myofibroblastic differentiation. Instead, the results suggest that these lesions are composed predominantly of cells of macrophage-dendritic cell lineage. Although the multiplicity of terms previously applied to these lesions is cumbersome, retaining a descriptive phenomenological terminology may ultimately promote accurate elucidation of pathogenesis.

Somatic mutations in the epidermal growth factor receptor gene (EGFR) are detected in a subset of lung adenocarcinomas, particularly bronchioloalveolar carcinoma (BAC) and adenocarcinoma with bronchioloalveolar features (AWBF), and correlate with clinical response to tyrosine kinase inhibitors (TKIs). In contrast, lung adenocarcinomas refractory to TKIs often have activating mutations in KRAS but lack EGFR mutations. Some adenocarcinomas have mucinous histology, but the clinical and molecular significance of the mucinous pattern is less well studied. We analyzed 43 BAC and AWBF tumors submitted for EGFR mutation testing to identify histopathological features that predicted EGFR or KRAS mutations. EGFR mutations were detected in 14 of 30 (47%) nonmucinous tumors, whereas 0 of 13 mucinous tumors harbored an EGFR mutation (P = 0.003). Missense mutations in KRAS codon 12 were detected in six of seven (86%) mucinous adenocarcinomas but only 3 of 18 (17%) nonmucinous adenocarcinomas (P = 0.003). Thus, in BAC/AWBF mucinous differentiation was significantly correlated with the absence of EGFR mutation and presence of KRAS mutation, suggesting that mucinous BACs/AWBFs are unlikely to respond to TKIs. Therefore, our data suggest that EGFR sequence analysis could be avoided in BAC/AWBF when true mucinous morphology is identified, avoiding the associated testing costs.

Pulmonary capillary hemangiomatosis (PCH) is an unusual disorder characterized by the proliferation of capillaries in the alveolar septa and pulmonary interstitium. Originally conceived as a primary idiopathic disorder of the pulmonary microcirculation, recent studies have demonstrated that PCH may be associated with other pathologies. Nitric oxide (NO) is a gaseous free radical with protean biological effects that is released during the intracellular conversion of arginine to citrulline. Nitric oxide synthases (NOS) mediate the production of NO and the release of NO in the microvasculature is specifically catalyzed by endothelial NOS (NOS-III). As NOS contributes to angiogenesis and is reduced in the hypertensive pulmonary microcirculation, we examined the expression of NOS-III protein in situ in the lungs of patients with PCH. Reduced microvascular expression of NOS-III protein by endothelial cells was observed in 4/6 (67%) cases of PCH, and all of these showed concomitant pulmonary vascular hypertensive remodeling. In 2/6 (33%) cases of PCH with no morphologic evidence of pulmonary hypertensive arteriopathy, endothelial expression of NOS-III protein was judged to be either minimally reduced or normal. These findings suggest that NOS-III is specifically reduced in PCH when pulmonary arterial hypertensive remodeling is concomitantly present.

Mucinous Cystadenoma of the LungAlexander R. Guimaraes1, John C. Wain2, Eugene J. Mark3 and Conrad Wittram1Audio Available | Share

A healthy 60-year-old patient presented with progressive dyspnoea. Clinical, radiographic and pathological features of interstitial lung disease were found and an open lung biopsy established the diagnosis of usual interstitial pneumonitis (UIP) (idiopathic pulmonary fibrosis). Despite treatment, the patient died 4 months later in respiratory failure. Although the patient had no extra-thoracic involvement at autopsy, his illness was associated with a very high titre of anti-double-stranded DNA antibodies, hypocomplementemia, hypergammaglobulinaemia and lymphoid hyperplasia. These features and a literature review, suggest immune-mediated lung damage in a subset of patients with UIP.

The histopathology of in-stent restenosis (ISR) following gamma brachytherapy is described. Such histology has not been reported previously. An 82 year old man presented with recurrent ISR three months after gamma brachytherapy to an area of ISR within a native circumflex vessel. The recurrent ISR was treated with directional coronary atherectomy; the histopathology of this directional coronary atherectomy specimen is discussed. These histopathological examinations showed abundant extracellular matrix material. Surprisingly, there was a relatively small cellular (myofibroblastic) component, with an absence of endothelial cells and little evidence of active proliferation. ISR after gamma brachytherapy may be a pathologically distinct entity.

The American Thoracic Society and the European Respiratory Society 2002 classification defines the histologic patterns that provide the basis for a clinico-radiologic-pathologic diagnosis of an idiopathic interstitial pneumonia. Idiopathic pulmonary fibrosis is the clinical term for usual interstitial pneumonia, the characteristic histologic pattern is interstitial fibrosis with temporal heterogeneity, and the radiologic pattern is basal and subpleural areas of ground-glass and reticular attenuation and honeycomb pattern. Nonspecific interstitial pneumonia has cellular or fibrosing patterns of chronic inflammation with temporal homogeneity; the radiologic pattern is subpleural and basal areas of ground-glass and reticular attenuation. Lymphoid interstitial pneumonia results from lymphocyte interstitial infiltration; CT demonstrates ground-glass attenuation and nodular interlobular septal thickening. Respiratory bronchiolitis-associated interstitial lung disease is characterized by bronchiolocentric alveolar macrophage accumulation; CT shows centrilobular ground-glass attenuation. Desquamative interstitial pneumonia is characterized by alveolar macrophage accumulation with predominantly lower zone ground-glass attenuation seen on CT scans. Cryptogenic organizing pneumonia is characterized radiologically by peribronchial ground-glass attenuation and subpleural consolidation. Acute interstitial pneumonia is the clinical term for idiopathic diffuse alveolar damage; the exudative phase is characterized radiologically by diffuse ground-glass attenuation and dependent consolidation, with the additional feature of lung architectural distortion in the organizing phase. Ideally, diagnosis of an idiopathic interstitial pneumonia should be rendered only after all clinico-radiologic-pathologic data have been reviewed.

A 49-year-old man with cirrhosis due to hepatitis C virus developed interstitial pneumonitis documented by surgical lung biopsy specimen evaluation after two weekly doses of pegylated interferon-alpha(2)b in combination with ribavirin. He developed ARDS and died after 26 days of hospitalization from multisystem organ failure. This case suggests that interstitial pulmonary disease can occur with pegylated interferon-alpha(2)b therapy.

We report here our experience in achieving remission in a 20-year-old man with pulmonary capillary hemangiomatosis (PCH) with atypical endotheliomatosis following therapy with doxycycline. PCH is a rare disorder characterized by proliferating capillaries that invade the pulmonary interstitium and alveolar septae, and occlude the pulmonary vasculature. The patient's symptoms, lung function, and radiographic findings had worsened despite treatment with both prednisone and alpha-interferon. He was considered to be a candidate for transplantation. Given the elevated levels of basic fibroblast growth factor (bFGF) in urine and the capillary proliferation noted on biopsy specimens, we elected to treat the patient with doxycycline, a matrix metalloproteinase and angiogenesis inhibitor. Following several weeks of therapy, a gradual resolution of symptoms was noted, with normalization of pulmonary function test results and urine bFGF levels. After 18 months of therapy, the patient remains in complete remission.