Tumor exhibits two or more distinct histological components: usually glandular (tubular/papillary) and signet ring cell/hypoadhesive

A malignant epithelial tumor that lacks glandular epithelial differentiation both cytologically and histologically.

Cancer cells are mostly spindle-shaped or round, arranged in sheets or bundles, and are more similar in shape to lymphoma or sarcoma. The immunohistochemical characteristics are positive for CK and Vimentin, suggesting that the cells are in an undifferentiated state.

Carcinoma with abundant lymphoid stroma (lymphocytic infiltration) and lack of glandular structures

Also known as medullary carcinoma with lymphoid stroma or lymphoepithelioma-like carcinoma, keratin and EMA positive

Hepatoid adenocarcinoma is composed of large polygonal cells with abundant eosinophilic cytoplasm, rich in glycogen, and transparent bodies. The morphological and immunohistochemical characteristics of the cancer cells are similar to those of hepatocellular carcinoma.

AFP-positive carcinomas consist of well-differentiated papillary or tubular adenocarcinomas with clear cytoplasm

Immunohistochemistry: AFP, GPC3, p53, SALI4, Hepatocyte polyclonal CEA (capillary bile duct-like staining) positive, Ki-67 staining showed high proliferation index

Adenocarcinoma and squamous components coexist, and at least 25% of the tumor is squamous cell carcinoma. Transition between the two components is seen, and lymphatic invasion is common.

Immunohistochemistry: Squamous cell carcinoma components are positive for p63, p40 and CK5/6

Tumors are composed of malignant epithelial cells and extracellular mucus pools, and the mucus component accounts for >50% of the tumor area.

Pattern 1: Recognizable glandular or tubular structures lined by columnar epithelium with stromal mucus secretion Pattern 2: Tumors are distributed in cords, nests, or individually (signet ring cells can be seen), and are surrounded by mucus

Tumor cells separate from each other or gather in small clusters without forming good glands

Signet ring cell type: composed mainly or only of signet ring cells. Signet ring cell carcinoma is less sensitive to chemotherapy. Non-signet ring cell type: includes tumors composed of tumor cells resembling histiocytes or lymphocytes, which may be accompanied by marked desmoplastic proliferation

CEA, EMA, Keratin, and Villin are positive, mucin, AB, and PAS are positive, E-Cadherin expression is decreased or missing, and TTF1 and p53 are negative.

Grossly exophytic growth pattern, elongated finger-like processes with fibrovascular axis

Lined with columnar or cuboidal cells, some tumors also contain small tubes (tubular papillae), usually well differentiated, pushing invasive edges, higher frequency of liver metastasis, and lower survival rate

Positive for holokeratin and low molecular weight keratin, positive for AB and PAS-D

The most common, consisting of heterogeneous glands with varying sizes, irregular shapes, or slit-like glands.

Tumors with tumor cells that are columnar, cuboidal, or flat, with solid architecture and barely identifiable tubules are also included in this classification, namely, poorly differentiated tubular (solid) carcinomas

AE1/AE3, EMA, MOC31, CK8/18, CK19 positive, CK7, CK20 may be positive in some cases