Imaging mass spectrometry (MS) is an emerging technique that can detect numerous biomolecular distributions in a non-targeting manner. In the present study, we applied a mass imaging modality, mass microscopy, to human lung tissue and identified several molecules including surfactant constituents in a specific structure of the lung alveoli. Four peaks were identified using imaging MS, and the ion at m/z 772.5, in particular, was localized at some spots in the alveolar walls. Using an MS/MS analysis, the ion was identified as phosphatidylcholine (PC)(16:0/16:0), which is the main component of lung surfactant. In a larger magnification of the lung specimen, PC (16:0/16:0) was distributed in a mottled fashion in a section of the lung. Importantly, the distribution of PC (16:0/16:0) was identical to that of anti-SLC34A2 antibody immunoreactivity, which is known to be a specific marker of type II alveolar epithelial cells, in the same section. Our experience suggests that imaging MS has excellent potential in human pathology research.

The present study investigates whether lymphatic vessel invasion (LVI) detected by D2-40 staining is a prognostic factor for stage I adenocarcinoma of the lung. We retrospectively reviewed 124 patients who underwent complete resection for stage I adenocarcinoma of the lung from January 1983 to June 2003. LVI was microscopically evaluated using D2-40 immunostaining. The median follow-up was 71 months. The LVI positive rate was 37%. The 5-year cancer-specific survival rates of the D2-40 positive LVI and negative groups were 88.8% and 84.3%, respectively (P = 0.630). The stage I lung adenocarcinoma patients who were determined to be LVI positive based on D2-40 immunostaining did not have a significantly poorer prognosis than the LVI negative cases. Thus, lymphatic microinvasion may not be a prognostic indicator in early lung cancer, although advanced LVI does appear to correlate with survival. It is therefore unnecessary to use D2-40 immunostaining to diagnose LVI in practical settings, and Hematoxylin-Eosin and Elastica van Gieson staining should continue to be used to predict the prognosis of patients with stage I lung adenocarcinoma.

The histologic characteristics of air space enlargement with fibrosis (AEF) are compared with usual interstitial pneumonia (UIP), nonspecific interstitial pneumonia (NSIP) and centrilobular emphysema (CLE) to determine similarities and differences. Lung specimens from 39 patients were studied; 9 with AEF, 13 with UIP and 5 with CLE identified in lobectomy specimens for cancer and 12 NSIP cases identified on surgical lung biopsies. We determined the characteristics of cystic structures (i.e. abnormal airspace), degree of inflammation and severity of pneumocyte injury semi-quantitatively. In AEF, the wall thickness of the cystic lesions (0.8 mm) was thinner than in UIP (2.1 mm) and thicker than in CLE (0.07 mm). The degree of inflammation and granulation tissue were milder in AEF than in UIP and NSIP and CLE showed milder inflammatory cells than AEF. As for pneumocyte injury, AEF had fewer erosions (0.1/case) and fewer ubiquitin-positive pneumocytes than UIP (4.8 cells/slide) and NSIP (9.8 cells/slide). Our data suggested that the histological characteristics of AEF differed significantly from UIP, NSIP and CLE.

A rare case of a mixed endometrial stromal and smooth muscle tumor arising in the uterus of a 74-year-old woman is reported. The patient underwent hysterectomy for an enlarging uterine mass, and a large intramural tumor, showing marked central hyaline necrosis with calcification, was found. The tumor consisted of an admixture of a low-grade endometrial stromal sarcoma (ESS) and a fascicular proliferation of spindle cells suggesting smooth muscle differentiation, and a characteristic ‘star-burst’ appearance was found. In the ESS region, there were a few small foci of anaplasia where large polygonal cells with atypical nuclei and abundant eosinophilic cytoplasm proliferated, and the proliferative activity was locally increased in these foci. A small metastatic nodule appeared in the lung nine months after the hysterectomy, and the resected metastatic lesion showed features of anaplastic spindle cell sarcoma which was immunoreactive for CD10 but not for smooth muscle markers. Mixed endometrial stromal and smooth muscle tumors should be regarded as malignant neoplasms with the potential for hematogenous metastasis, particularly when they contain foci of cellular anaplasia.

Well-differentiated papillary mesothelioma (WDPM) is a distinct subtype of mesothelial tumor from diffuse malignant mesothelioma (DMM), with an uncertain malignant potential. The relationship between WDPM and DMM, with regard to the ability of the former to develop into the latter, is also unknown. A 58-year-old woman, diagnosed with a rectal carcinoid tumor, underwent removal of the lymph nodes via the abdomen in 2004. A large number of white miliary nodules were identified on the mesentery and peritoneum, which were histologically diagnosed as WDPM. No further therapy was administered, but the patient was followed-up using imaging methods. Seven years later, an abdominal wall mass was discovered using positron emission tomography-computed tomography, and a laparotomy biopsy was performed. DMM was diagnosed, because mesothelioma with extended invasion had been histologically identified. Mesothelioma similar to papillary proliferation was present on the outer layer of the peritoneum, and an infiltrating lesion with continuous restiform or solid-like structures was noted. WDPM was believed to have undergone malignant transformation. Compared to DMM, WDPM has a good prognosis and is considered a benign or borderline neoplasm. Our findings suggest that WDPM does have malignant potential, however, because histological findings indicated a malignant transformation of WDPM to DMM.

Fibrocartilaginous mesenchymoma (FCM) of the bone is a rare tumor, with only 21 reported cases since 1984. It usually occurs in the long bones of children and adolescents, but in this case, the tumor arose in the pubic bone. The pathological diagnosis of FCM can be challenging, and the treatment should be a wide resection because of its locally aggressive behavior. Histologically, our tumor was composed of a lobular proliferation of spindle cells juxtaposed to the cartilaginous tissue, lacking cytological atypia. Enchondral ossification was observed at the periphery of the cartilaginous nodules, and hypertrophic chondrocytes was recognized, reminiscent of an epiphyseal plate. Intralesional resection followed by phenol and ethanol cauterization was performed in place of the usual wide resection. We report a case of FCM arising in a rare anatomical site, the pubic bone, successfully treated by intralesional resection. One year after the surgery, the patient is free of disease.