Collision Tumors of the Colon and Peritoneum: Signet-Ring Cell Carcinoma and Granular Cell Tumor.

Collision tumors, although rare, characterized by two distinctive (morphological, as well immunohistochemical) and spatially independent tumor components at the same location, are always puzzling for clinicians, pathologists, and patients because they do not fit into the usual approaches, being neither diagnostic nor therapeutic. Reviewing the specialized literature, to date, collision tumors have been reported in multiple locations such as the skin, esophagus, stomach, intestine, liver, kidney, bladder, adrenal gland, or thyroid. We report a case of coexistence at the same site of a malignant tumor of the ascending colon and a benign tumor emerging from the peritoneal lining, initially thought by the surgeon to be right-sided serosal carcinomatosis. But histopathological examination reveals that those multiple serosal nodules were benign granular cell tumors that have collided with highly aggressive transparietal signet-ring colon carcinoma. These results put the patient's prognosis and therapeutic strategy in a different light than the clinical and intraoperative evaluation.

Analysis of Tumor Depth Invasion With Anti-Smoothelin Antibody in Equivocal Transurethral Resection of Urinary Bladder Tumor Surgical Specimens.

OBJECTIVE: To examine the expression and value of the smoothelin marker in control cases, to standardize the working method, and to analyze its application in pathologic staging process of problematic transurethral resection of bladder tumor (TURBT) cases. MATERIAL AND METHODS: Immunohistochemical (IHC) staining was performed on tumor-free bladder wall sections, tumor-free large bowel sections, TURBTs with unequivocal tumor stage, and TURBTs with equivocal stage. The IHC staining of muscularis mucosa (MM), muscularis propria (MP), and blood vessels was evaluated semiquantitatively. RESULTS: Smoothelin IHC staining pattern ranged from negative (30% to 67% cases) to 2+ (0% to 15% cases) in MM and from 1+ (10% to 50% cases) to 3+ (9% to 48% cases) in MP. When compared on the same slide, the smoothelin expression of MP showed a stronger staining intensity than the one of the MM in all the analyzed cases. Blood vessel muscle cells stained in a constant intensity as the MM (r = 0.9808; r = 0.9604). Smoothelin determined restaging of 33% of the problematic TURBT cases. CONCLUSION: Smoothelin is an IHC marker that shows differential staining between coexistent MM and MP; however, variations in staining intensity and pattern may occur, aspects that can be influenced by different technique variables. We recommend using this marker as a diagnostic tool in problematic TURBT cases only when there is sufficient experience in control cases with this antibody.

Pseudobenign prostate carcinomas: causes of false-negative biopsy results.

Prostate carcinomas are continuously surprising the pathologists through their multitude of variants and histological subtypes, some of them being recently described and characterized. Among these are individualized: atrophic carcinoma, foamy gland, pseudohyperplastic, microcystic, certain subtypes of ductal adenocarcinoma and hormone-treated adenocarcinoma, which because of minimal architectural and/or cytological atypia are often under-diagnosed, especially in small tissue fragments. This paper presents the morphological criteria, including information provided by some immunohistochemical markers for positive and differential diagnosis of these variants/subtypes of prostate adenocarcinoma with which the pathologist should be familiar and avoid their confusion with a series of similar histological structures or benign/premalignant lesions.

Prostate lesions with cribriform / pseudocribriform pattern.

Prostate lesions with cribriform / pseudocribriform architecture range from normal histological structures to infiltrative carcinoma. In each group of lesions with cribriform architecture (benign, premalignant and malignant intraductal or infiltrating), there are situations in which histological classification of the lesion is difficult or impossible on routine stains. A more wide-scale application of the immunohistochemical investigation for clearing up the problematic prostate lesions led to the definition and reclassification of cribriform lesions in distinct categories and sometimes very different in terms of progression, prognosis and treatment. This paper proposes an overview of the prostate lesions with cribriform / pseudocribriform architecture, emphasizing the morpho-immunohistochemical criteria for positive and differential diagnosis.

Prostatic blue nevus.

We report the case of a 69-year-old patient with no significant personal urological history. The clinical and ultrasound examination revealed a prostatic gland with increased volume and homogenous appearance. After transurethral resection, multiples gray-brown-blackish prostatic chips were obtained, which could be confused with a malignant melanoma. The histological routine examination in conjunction with the histochemical (Fontana-Masson) and immunohistochemical (S100, HMB45) reactions established the diagnosis of prostatic blue nevus. The presence of melanin in prostatic tissue is an unusual aspect, being encountered three distinct lesions: blue nevus, melanosis and malignant melanoma. Recognition and correct classification of each of these three entities is fundamental, concerning the clinical and prognosis implications.