Variation in (18)F-FDG PET findings in a patient with synchronous multiple thymoma.

We herein present a case of synchronous multiple thymoma that was suspected based on the findings of positron emission tomography with fluorine-18-labeled-fluorodeoxyglucose ((18)F-FDG PET). The patient was a 70-year-old male with two similarly sized and heterogeneously enhanced masses on the right side of the anterior mediastinum on chest computed tomography. (18)F-FDG PET revealed variation in FDG accumulation between the masses, in which the maximum standardized uptake value was 4.4 in Tumor 1 and 8.7 in Tumor 2. Based on these imaging findings, the masses were suspected to be independent, likely synchronous double primary thymoma. Total thymectomy with removal of the two tumors was performed via median sternotomy. A pathological examination identified Tumor 1 as type AB thymoma and Tumor 2 as type A thymoma. This is the first reported case of synchronous multiple thymoma which was suspected based on a variation in the (18)F-FDG PET findings between the tumors.

Pulmonary adenosquamous carcinoma with mucoepidermoid carcinoma-like component with characteristic p63 staining pattern: either a novel subtype originating from bronchial epithelium or variant mucoepidermoid carcinoma.

BACKGROUND: Our previous study found unique adenosquamous carcinomas (ADSQs) containing a mucoepidermoid carcinoma (MEC)-like component and a characteristic p63 staining pattern. This study focused on these unique ADSQs. METHODS: Thirty ADSQ cases were studied histologically and by immunohistochemistry for TTF-1 and p63. Of these 30 ADSQs, eight were selected as unique ADSQs. The clinicopathological characteristics of these ADSQs were further studied, and the gene rearrangement of mammalian mastermind-like 2 (MAML2) was investigated by fluorescence in situ hybridization (FISH) for differentiation from pulmonary MEC. RESULTS: The clinicopathological characteristics between the eight ADSQs and the other ADSQ cases showed no statistically significant differences, except for serum CEA level. Histologically, the eight ADSQs contained varying degrees of the MEC-like component, which consisted of solid nests with mucin-filled cysts or a cribriform-like structure. Immunohistochemically, p63-positive nuclei characteristically encircled the tumor nests, although TTF-1 was completely negative. All unique ADSQs not only had a variable degree of squamous cell carcinoma component in addition to the MEC-like component, but also contained a small tubular adenocarcinoma component in three tumors. FISH analysis revealed no MAML2 gene rearrangement in the eight ADSQs. CONCLUSIONS: Of the 30 ADSQs investigated in this study, eight contained a MEC-like component with a characteristic p63 basilar staining pattern similar to that of bronchial basal cells. These unique ADSQs shared clinical characteristics with ordinary ADSQs, but clinicopathologically differed from pulmonary ordinary MEC. Therefore, these unique ADSQs may be either a novel ADSQ subtype originating from bronchial epithelium or variant-type MEC.

A clinicopathological and immunohistological re-evaluation of adenosquamous carcinoma of the lung.

Since the World Health Organization histological criteria were published in 1999, several studies have focused on adenosquamous carcinoma of the lung. Therefore, we aimed to clinicopathologically re-evaluate this tumor using immunohistochemical methods. In our hospital, there have been 21 surgically resected adenosquamous carcinomas. The frequency of adenosquamous carcinoma was 1.9% and the clinical data including the patient prognosis data obtained in this study were similar to those reported previously. A fluorodeoxyglucose positron emission tomography study first revealed that the median maximum standardized uptake value of adenosquamous carcinoma was 9.3 and ranged from 2.0 to 24.5. According to the results of immunohistochemical staining for thyroid transcription factor-1 (TTF-1) and p63, adenosquamous carcinomas were divided into four subgroups: group 1, TTF-1+ and p63+ (10 cases); group 2, TTF-1- and p63+ (six cases); group 3, TTF-1+ and p63- (three cases); and group 4, TTF-1- and p63- (two cases). Of the six group 2 tumors, three were composed of unique solid nests with mucin-filled cysts and showed characteristic p63 expression, which might suggest a special type of adenosquamous carcinoma. Immunohistochemical analysis of TTF-1 and p63 expression shows that adenosquamous carcinoma is composed of diverse tumor groups, for which the biological and histogenetic nature further needs to be clarified.

Expression of podoplanin in thymoma: its correlation with tumor invasion, nodal metastasis, and poor clinical outcome.

Recent studies have shown that podoplanin overexpression is associated with lymph node metastasis and poor clinical outcome in several malignant tumors. To investigate the role of podoplanin in thymoma, we examined 111 thymomas by immunohistochemistry using monoclonal antibody D2-40, which recognizes podoplanin. The tumors consisted of 8 type A, 40 type AB, 15 type B1, 23 type B2, 15 type B3, and 10 combined thymomas according to the World Health Organization histological classification system and of 41 stage I, 28 stage II, 16 stage III, 20 stage IVa, and 6 stage IVb thymomas according to the Masaoka staging system. We have found podoplanin expression in 0 (0%) type A, 4 (10%) type AB, 4 (27%) type B1, 16 (70%) type B2, 10 (67%) type B3, and 7 (70%) combined thymomas and in 5 (12%) cases of stage I, 7 (25%) of stage II, 11 (69%) of stage III, 12 (60%) of stage IVa, and all (100%) of stage IVb thymomas. Podoplanin was significantly expressed in B2/B3/combined thymomas and advanced stage thymomas (P < .0001). On survival analysis, podoplanin expression was significantly associated with an increased risk of death for the whole group of thymomas (P = .0002), although it was not identified as an independent prognostic factor in multivariate analysis. The significant survival curve differences of podoplanin expression were also seen for stage III/IVa/IVb thymomas (P = .0409) and B2/B3/combined thymomas (P = .0478). In conclusion, D2-40 immunostaining seems to be valuable for predicting the aggressive and metastatic potential of thymomas and the prognosis of the patients.