Gross pathology image of a resected sigmoid colon segment showing a bulky colorectal carcinoma. The tumor mass is exophytic, lobulated, and red-purple in color, with irregular, friable surfaces and clear demarcation from adjacent normal mucosa. The anal mucosa is visible to the right of the lesion, illustrating the tumor’s distal extent toward the rectosigmoid junction. A 2 cm scale bar is provided for size reference. The lesion distorts the colonic wall with thickening and luminal narrowing, consistent with invasive growth through the mucosa and into the submucosa and muscularis propria in a gross examination. Gross variants described in literature include exophytic polypoid masses, flat/depressed ulcerating infiltrative lesions, napkin-ring constrictions in distal colon, mucinous gelatinous appearances, and signet-ring cell related linitis plastica in advanced disease; these features are not all simultaneously present here, but the image exemplifies exophytic-type colorectal carcinoma. This macroscopic morphology correlates with potential lymphovascular invasion and nodal metastasis risk, and it supports clinical staging and surgical decision-making. The specimen’s appearance provides valuable educational context for understanding colorectal cancer pathology, morphology, gross differential diagnoses (polypoid adenocarcinoma, ulcerative cicatrix), and correlation with imaging and endoscopic findings. This image supports educational reference for residents, pathologists, and gastroenterology trainees in clinic and research settings.

Gross pathology photograph of a resected sigmoid colon specimen showing a serosal surface densely studded with grayish-white, firm to soft nodules. The nodules are subserosal in location, compressing underlying adipose tissue and focal serosal irregularity is evident. The appearance is characteristic of serosal implants seen with advanced colorectal neuroendocrine carcinoma. The primary tumor is in the sigmoid colon; the nodules on the outer serosal surface suggest peritoneal dissemination or subserosal metastatic spread. The color is pale gray to pink-turquoise with a glistening, lobulated contour in places. The surrounding colonic wall shows irregular thickening and mucosal involvement consistent with an aggressive neuroendocrine tumor; vascular congestion is mild. In the clinical setting, such gross features raise concern for metastatic disease and peritoneal carcinomatosis; histopathology would reveal sheets of neuroendocrine cells with immunohistochemical positivity for chromogranin A and synaptophysin, high mitotic activity, and a high Ki-67 index. This image is valuable for education on gross morphology of colorectal neuroendocrine carcinomas and their serosal metastases, contributing to differential diagnosis with carcinoid tumors, adenocarcinoma metastases, and granulomatous processes. It supports imaging-pathology correlation, surgical pathology review, and teaching scenarios in gastrointestinal oncology. These features underscore the importance of correlation with clinical staging.

This endoscopic clinical image displays a colonoscopy view of the sigmoid colon, revealing an advanced, obstructive colorectal carcinoma. The pathology presents as a bulky, circumferential mass that causes severe luminal stenosis, nearly completely occluding the intestinal passage. The tumor surface is markedly irregular and nodular, exhibiting a predominantly pinkish-red color with dark red hyperemic patches suggestive of friability and potential hemorrhage. Areas of yellowish-tan discoloration are visible on the mass, which may indicate surface necrosis or mucinous components. Surrounding the lesion, the lumen contains yellowish-brown, translucent fluid with small air bubbles and suspended particulate matter. The image illustrates a critical case of obstructive colitis, highlighting the characteristic morphology of a moderately differentiated adenocarcinoma in a geriatric clinical context.

Educational medical composite featuring preoperative imaging and gross pathology of a sigmoid colon carcinoma. Panel (a) is an axial contrast-enhanced CT scan of the pelvis showing a large, heterogeneous, hypodense mass approximately 12 cm in diameter (delineated by a yellow dotted line). The imaging demonstrates suspicion of direct invasion into the adjacent rectum (blue arrows) and uterus (yellow arrows). Panel (b) shows a macroscopic photograph of the resected surgical specimen alongside a measurement scale. The specimen contains the sigmoid colon and uterus, revealing a bulky, irregularly shaped Type 1 tumor (outlined with a red dotted line) measuring 130 x 40 x 25 mm. The gross findings confirm direct local invasion into the uterine corpus, ovary, and small intestine. This case illustrates clinical Stage IIC (T4bN0M0) colorectal adenocarcinoma, emphasizing the visual characteristics of locally advanced disease and the importance of multidisciplinary surgical planning for multi-organ resection.

Histopathology slide of colorectal tissue examined under light microscopy after Hematoxylin and Eosin staining. The specimen architecture shows a mucinous variant of colorectal adenocarcinoma characterized by moderately differentiated neoplastic glands embedded in abundant extracellular mucin pools within a conspicuous desmoplastic stroma. Neoplastic glands display epithelial atypia with nuclear pleomorphism, hyperchromasia, and increased mitotic activity, arranged in back-to-back glands with cribriform or clustered patterns interspersed within mucin lakes. The tumor produces copious mucin which displaces adjacent stroma and forms lakes that are partially lined by neoplastic epithelium. The surrounding stroma is fibrous and dense (desmoplastic), with inflammatory infiltrates and occasional hyalinization. No evident invasion of vessels or nerves is clearly visible at this low magnification, but the desmoplastic reaction supports invasive carcinoma. The mucinous phenotype has clinical implications: often associated with higher stage at presentation, potential for peritoneal dissemination, and variable response to chemoradiation. This image is indicative of colorectal cancer of mucinous subtype and underscores the importance of recognizing mucin-rich histology as a distinct clinicopathologic entity with prognostic and therapeutic relevance. Correlation with immunohistochemical profiles (CK20, CK7, MUC2, MUC5AC, CEA) can aid differential diagnosis, confirm lineage, and guide targeted therapy decisions in multidisciplinary tumor boards for optimal patient management today.

Imaging modality and technique: light microscopy of a formalin-fixed colorectal tissue section stained with Hematoxylin and Eosin (H&E). In this mucinous variant of colorectal adenocarcinoma, the tumor demonstrates abundant extracellular mucin pools separating irregular, branching or anastomosing neoplastic glands. The glands are lined by tall, columnar epithelium with goblet-cell–like mucin cytoplasm; cytologic atypia is generally minimal and mitotic activity is relatively low compared with high-grade conventional adenocarcinoma. The neoplastic cells project into mucin lakes, producing a characteristic sign of mucinous histology. The surrounding stroma may be looser or inflammatory, and residual non-neoplastic mucosa is variably present at the periphery. The histologic pattern may be accompanied by mucin-positive secretions within glands and throughout the extracellular matrix. This morphological subtype frequently correlates with distinctive molecular features, including mucin expression patterns such as MUC2 predominance, and possibly MUC1/MUC3 in other variants; serrated variants may show MUC2/MUC5AC/MUC6 upregulation. Clinically, mucinous colorectal carcinomas tend to present at a different stage distribution and may have different prognostic implications compared with conventional colorectal adenocarcinoma. Immunohistochemical profiling for mucin core proteins can aid classification and guide targeted therapeutic considerations, with potential implications for surgical planning and adjuvant therapy choices.

Imaging modality: Light microscopy of a hematoxylin and eosin (H&E) stained colorectal tissue section. Primary subject: Mucinous variant of colorectal adenocarcinoma with moderately differentiated neoplastic glands surrounded by abundant extracellular mucin in a desmoplastic stroma. The histology shows clusters of malignant glandular units lined by columnar epithelial cells with moderate cytologic atypia, nuclear pleomorphism, and irregular contours. These glands are interspersed with large lakes of mucin, which displace and pull apart the surrounding fibrous stroma. The desmoplastic reaction appears as dense, fibrous connective tissue with activated myofibroblasts and sparse inflammatory cells. Glandular architecture is irregular and commonly displays cribriform or back-to-back patterns, with variable mitotic activity. The tumor demonstrates notable mucin production both within gland lumina and as extracellular mucin pools; this mucinous pattern typically lacks cohesive invasion in some areas but can invade through the muscularis propria. Diagnostic significance: histologic confirmation of a mucin-producing colorectal carcinoma, with implications for prognosis and therapeutic planning; mucin-rich tumors can have distinct molecular features (e.g., mismatch repair deficiency) and may influence response to chemotherapy. The image is relevant for diagnostic pathology review, tumor classification, educational illustrate mucinous differentiation, and oncologic decision-making. Correlation with clinical presentation and imaging aids comprehensive assessment and management planning.

Imaging modality: Gross pathology photograph of a colectomy specimen with extensive mucosal polyposis. Primary subject: Familial Adenomatous Polyposis (FAP) characterized by hundreds to thousands of colonic polyps. Specimen type: colectomy (colon) showing a broad, polyp-dense mucosal surface. Imaging perspective: exterior view of longitudinally oriented colon segments, highlighting the mucosal polyp burden. Detailed description: The colon shows a remarkable burden of tiny polypoid lesions distributed across the mucosa. Most polyps are diminutive, under 1 cm in greatest diameter, giving a rough, nodular surface with a cobblestone appearance. The tissue coloration is a uniform reddish-pink. The polyps arise from the colonic mucosa with variable pedunculation; adenomatous-type appearance is suggested by their regular rounded contours and granular surface. This gross phenotype aligns with classic FAP, often associated with APC gene mutations, particularly around codons 1250-1464 (notably near codon 1300), producing profuse polyp formation. Mutations toward the extreme 5' and 3' ends yield attenuated polyposis. In this case, the description notes that approximately 25% of patients harbor colorectal cancer at colectomy. Clinically, such specimens illustrate the rationale for prophylactic colectomy to mitigate near-certain cancer risk. Credit: image courtesy of Dr. Jean-Christophe Fournet; humpath.com; Used with permission.

This clinical photograph shows a gross pathological total colectomy specimen from a patient with Familial Adenomatous Polyposis (FAP). The resected colon is opened longitudinally to reveal the mucosal surface. The image displays the caecum and ascending colon in the lower section, with the descending colon positioned above. The most prominent feature is the extensive, dense distribution of hundreds of adenomatous polyps across the mucosal lining, creating a characteristic 'carpeted' appearance. Centrally located in the upper portion of the specimen is a visible surgical site corresponding to a previous anastomosis. The tissue appears erythematous and fleshy, typical of a fresh surgical specimen. This image serves as a classic educational example of the phenotypic manifestation of FAP, illustrating the necessity of radical surgical intervention due to the high density of precancerous lesions throughout the colorectal tract.