Types of Metastatic Cutaneous Squamous Cell Carcinoma

This is the fourth part of our series about the condition based on our patient booklet “Fast Facts for Patients and their Supporters: Advanced Cutaneous Squamous Cell Carcinoma”. This article deals with the types of metastatic cutaneous squamous cell carcinoma.

Metastatic Cutaneous Squamous Cell Carcinoma

Why Does cSCC Spread?

It is rare for cSCC to spread to another place in the body. But there are some high-risk features of the primary cSCC that make this more likely, including:

large size (over 2 cm)
cancer recurs (comes back) in the same location after surgery
it affects the ear or lip.

There are also some features that can be seen in the laboratory from the biopsy:

the nerves are involved
the cancer cells are poorly differentiated, which means they appear spindle shaped or different from usual cancer cells
the cancer has created a different-looking area around itself (called desmoplasia)
the cancer has grown (invaded) deeply through the skin to the fat, muscle or bone underneath.

cSCC is also more likely to spread in a person whose immune system is suppressed – which happens with some conditions, such as leukemia, lymphoma and HIV/AIDS, and after an organ transplant.

What Are the Different Types of Metastases?

Regional and In-Transit Metastasis

The lymphatic system is made up of small vessels and lymph nodes. It runs through the body alongside blood vessels. (Lymph nodes = “glands”.)

It’s an important part of the immune system as it provides a way for immune cells to circulate around the body.

When cSCC spreads, or metastasizes, to other parts of the body, it typically travels through the lymphatic system or the bloodstream.

cSCC cells that invade the lymphatic system can travel to the lymph nodes and grow there. When the affected lymph node is close to the original tumor, it’s called regional metastasis.

Very rarely, cSCC spreads through the lymphatic system and grows in multiple tumors under the skin along the lymphatic route. This is called in-transit metastasis.

Distant Metastasis

Distant metastasis happens when cSCC cells travel past the regional lymph nodes to lymph nodes or organs in other places in the body, as shown on the diagram: