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. Author manuscript; available in PMC: 2017 Feb 1.
Published in final edited form as: Mod Pathol. 2015 Nov 6;29(2):122–130. doi: 10.1038/modpathol.2015.109

Figure 1.

Figure 1

Figure 1

Figure 1

Figure 1

Figure 1

Patterns of lymph node involvement by Merkel cell carcinoma

A. Pattern 1 was characterized by a solid, sheet-like proliferation of metastatic tumor. Immunohistochemistry was not needed to identify metastatic tumor in these cases (H&E).

B. Pattern 2 was characterized by a non-solid proliferation of tumor cells in the parafollicular lymph node cortex (CK20 immunohistochemical stain)

C. Pattern 3 was characterized by variable numbers of tumor cells in the subcapsular sinus (CK20 immunohistochemical stain).

D. Pattern 4 was characterized by clusters of tumor cells around larger vessels in the lymph node hilum. This was the least common pattern of metastasis (CK20 immunohistochemical stain).

E. Pattern 5 was characterized by isolated rare tumor cells in the lymph node parenchyma. This pattern of metastasis was only detected by immunohistochemistry (CK20 immunohistochemical stain).