A distinction is made between skin carcinomas, mucosal carcinomas and urothelial (paramalpighial, transitional cell) carcinomas.

Carcinomas of the skin

They are very common, especially in open and sun-exposed areas, such as the face and hands. They develop on healthy skin or solar keratosis (actinic) for example.

Diagnosis is easy, as is the biopsy performed.

There are two main types: basal cell carcinomas and squamous cell carcinomas.

Spinocellular carcinoma

• Macroscopy : it is an ulcerous budding or vegetative tumor.
• Microscopy : the tumour consists of a trabecular or lobulated proliferation of very coherent cells with union bridges or spines, hence the name "spinocellular".

The carcinoma is more or less well differentiated with signs of keratin maturation that can produce true horny globes (concentric keratin flakes).

• Evolution : squamous cell carcinoma has a local extension. Satellite nodes may be invaded but visceral metastases are exceptional.

Basal cell carcinoma

A basal cell carcinoma is being investigated by a doctor. It often appears as a raised, painless area of skin that may be shiny with small blood vessels.

• Macroscopy : it's an ulcerated plaque tumor that's more than vegetative.
• Microscopy : the proliferation is arranged in clumps or trabeculae of cells having the appearance of basal cells of the normal epidermis. Its adnexal origin is admitted. Mitosis and atypia are more or less numerous.
• Evolution : local ulcer-infiltration evolution is slow. Importantly, there is never metastasis.

Mucosal carcinoma

These carcinomas are of the squamous or cylindrical type, but their macroscopic features are quite similar. Their diagnosis has largely benefited from endoscopic techniques with directed biopsies.

Macroscopy

• Vegetative (or budding) tumour

Example: Colonic cancer can obstruct the lumen of the colon, causing an occlusion.

• Ulcerative tumor

Example: destruction of the colonic wall by an adenocarcinoma. In fact ii is most often an ulcerous budding tumour.

• Infiltrating tumor

Example: a gastric carcinoma with an important fibrous stroma-reaction infiltrates the wall which becomes thick and rigid, which made it named "plastic linite". A bronchial cancer stenoses the lumen by progressive infiltration of the bronchus.

In practice, the macroscopic aspect depends on the stage at the time of diagnosis. It is most often an ulcerative and infiltrating tumour.

Microscopie

Undifferentiated carcinoma

They are cellular layers without any architectural arrangement evoking a precise tissue origin and without any sign of differentiation towards a squamous or glandular tissue. These carcinomas are ubiquitous. Their diagnosis is largely based on an immunohistochemical study (see: cancerous tissue).

Carcinomas more or less well differentiated

• MALPIGHIANS

When these carcinomas are well differentiated with union pants, they are reminiscent of the epidermis, hence the term "EPIDERMOIDE". The presence of keratin is variable and it can adopt ortho, para or dyskeratotic aspects. This keratin is a translation of the maturation of the cancer as in the case of squamous cell carcinoma of the skin. The most frequent locations are the oesophagus, the ENT and oral sphere, the anal canal and the cervix.

• glandular or ADENOCARCINOMES

Proliferation is well differentiated when it forms clearly visible glands, sometimes regular or forming tubules or papillae. Less differentiated, it forms confluent spans or layers.

Cell differentiation is also expressed by the production of mucus, alcian blue and PAS positive. This secretion can be observed in the cytoplasm giving aspects of "kitten ring" cells, but it can also be poured into the stroma realizing puddles of mucus = adenocarcinorne "mucous colloid".

The main seats are the stomach, the colo-rectum and the endometrium.

So-called metaplastic carcinomas

Carcinoma is then different from matrix tissue that has undergone metaplasia prior to the malignant transformation. This is the case with more or less well differentiated squamous cell carcinoma of the bronchus or gastric adenocarcinoma of the intestine type.

Evolution

The evolution is local with metastatic satellite lymph node involvement towards the different viscera.

Urothelial carcinomas (paramalpighial, transitional cell carcinomas)

Location

These carcinomas sit on the whole excreto-urinary tree (BLEEP+++), making a real disease of the urinary tree: this explains the recurrences and especially the progressive aggravation after endoscopic resection. Next to the very rare benign tumour called papilloma, (hands of 1%) most urothelial tumours are carcinomas.

Macroscopy

• generally papillary vegetal form with a more or less wide implantation on the wall: the most frequent.
• extension on the surface: the carcinoma remains non-invasive for a long time = in situ.
• later invasive form
• often also a combination of the three previous forms.

Microscopy

• Papillary urothelial carcinoma, based on cellular atypia and mitosis on the papillary fringes, can be classified into three groups or WHO I, II and III grades of increasing severity.
• In the second stage, the infiltrating phase is vertical and massive especially in grade III carcinomas.

Evolution

It is done in a recurrent mode with aggravation of the lesions although for a very long time locally. In a second stage the evolution is loco-regional with the possibility of metastatic adenopathies, then towards the pelvis with visceral metastases such as bone or lung.