Perineurioma versus meningioma. A multi-institutional immunohistochemical and ultrastructural studY.

The differential diagnosis between perineurioma (PN) and meningioma (MEN) can be difficult by histology and immunohistochemistry (IHC) because the perineurium and arachnoid have the same embryological origin. However, there are no comparative studies determining conclusive parameters for the differential diagnosis. The aim of this study is to compare IHC of PN and MEN and their ultra-structural characteristics to elucidate which are the useful data that allow differentiate both entities. Thirty-five MEN were analyzed, and 15 PN, (11 skin and soft tissues and four oral cavity). IHC for epithelial membrane antigen (EMA), Claudin-1, GLUT-1, somatostatin-2 receptor (SSTR-2), and progesterone receptor (RP) was performed. Ultrastructural studies were performed on 8 MEN and 15 PN. Only in PN Claudin-1 was positive in 9/11 (90%) cases and GLUT-1 in 7/11 (63%) cases. In MEN, the progesterone receptor was expressed in 21/35 (60%) cases and no case expressed Claudin-1 and GLUT-1; EMA was expressed in all MEN cases and 93% of PN. SSTR-2 was expressed weakly in six cases of MEN (17%), and it was not considered useful for differential diagnosis. On ultrastructure, PN showed thin and parallel processes, some caveolae, and lacked cell junctions. The cellular processes were surrounded by a collagenous stroma in 94% of the cases. MEN were characterized by curved cytoplasmic cell processes showing desmosomes in 75% of cases. Ultrastructural findings aid in the differential diagnosis between PN and MEN, especially if molecular studies are not available.

Mantle cell lymphoma with involvement of the digestive tract. / Linfoma del manto con afección del tubo digestivo.

INTRODUCTION AND AIM: Mantle cell lymphoma is an aggressive subtype of B-cell non-Hodgkin lymphoma and its incidence is 0.5/100,000 inhabitants. Gastrointestinal involvement at diagnosis is 15-30%. The aim of our study was to analyze the clinical and endoscopic characteristics of mantle cell lymphoma affecting the digestive tract. MATERIAL AND METHODS: A retrospective study was conducted, based on a case series of patients with mantle cell lymphoma affecting the gastrointestinal tract that were diagnosed over a 10-year period. RESULTS: Ten patients (11.7%) had gastrointestinal tract involvement. The upper endoscopic findings were polypoid lesions (66%), thickened folds (44%), and nonspecific changes in the mucosa (33%). At colonoscopy, polypoid lesions were viewed in 100% of the patients and ulcerated lesions in 40%. CONCLUSION: Polypoid lesions are the most common endoscopic characteristics in patients with mantle cell lymphoma of the gastrointestinal tract. Upper endoscopy and colonoscopy should be carried out on patients with mantle cell lymphoma, even those with nonspecific symptoms, to check their gastrointestinal status. Gastrointestinal involvement has an impact on disease staging.

Colonic micropapillary carcinoma, a recently recognized subtype associated with histological adverse factors: clinicopathological analysis of 15 cases.

AIM: Micropapillary carcinoma (MPC) is regarded as an aggressive variant of adenocarcinoma in any location. The reported proportion of a micropapillary carcinoma component in an entire tumour ranges from 5 to 95% and only one case of pure MPC has been reported. To date, approximately 130 cases of MPC in the colorectum have been reported, but it is likely that this small number is to some extent due to under-reporting because this pattern is not well recognized by the general pathologist. All previous studies have combined colonic and rectal primary tumours and most have only analysed patients with clinical Stages I or II. METHOD: We analysed 15 cases of MPC of the colon alone, diagnosed in our institution, and compared them with 105 conventional carcinomas of the colon. RESULTS: An MPC component was present in 10% of all colonic carcinomas. These tumours presented at a median age of 56 years, and all were of American Joint Committee on Cancer Stages III and IV. Subserosal tissue invasion was present in every case, 60% had more than four positive lymph nodes, 60% were accompanied by poorly differentiated conventional carcinoma, 40% had had an incomplete resection and a third demonstrated lymphovascular invasion. Despite these adverse prognostic factors, tumours containing MPC showed the same survival, stage by stage, as conventional adenocarcinoma in multivariate analysis, although 3-year survival (81.7%vs 87.3%, P=0.035) was worse on univariate analysis. CONCLUSION: The histopathologist should be aware of the possibility of MPC. Three-year survival is worse than in patients with conventional colonic carcinomas in Stage III.