Intratumoral and Peritumoral Lymphovascular Invasion Detected by D2–40 Immunohistochemistry Correlates with Metastasis in Primary Cutaneous Merkel Cell Carcinoma

Publication date: Available online 28 March 2018
Source:Human Pathology
Author(s): Rami N. Al-Rohil, Denái R. Milton, Priyadharsini Nagarajan, Jonathan L. Curry, Laurence Feldmeyer, Carlos A. Torres-Cabala, Doina Ivan, Victor G. Prieto, Michael T. Tetzlaff, Phyu P. Aung
Primary cutaneous Merkel cell carcinoma (MCC) is an aggressive neuroendocrine malignancy in which lymphovascular invasion (LVI) correlates with more aggressive phenotype. The prognostic significance of LVI detected by D2–40 immunohistochemistry (IHC) in MCC remains controversial. We aimed to determine how LVI detected by D2–40 IHC compares with LVI detected by hematoxylin–eosin (H&E) staining in predicting MCC metastasis. Clinical and histopathologic features of MCCs diagnosed and treated during 2002–2015 were assembled and included 58 MCC tumors from 58 patients. H&E stained tissue sections and D2–40 immunohistochemical studies were reviewed. When LVI was present, the location (peritumoral or intratumoral) and the size of the largest invaded vessel were recorded. LVI findings by H&E staining and D2–40 IHC were compared to each other and with histologic features and clinical outcomes. H&E staining showed LVI in 37 of 58 cases; D2–40 IHC confirmed LVI in 30 of these cases but failed to confirm LVI in 7. D2–40 IHC also detected 14 cases of LVI not identified on H&E staining. Histologically, D2–40 detected LVI associated with infiltrative growth pattern and non-brisk lymphoid infiltrate (P=.005 and P=.055, respectively). There was a statistically significant difference between the frequency of detection of peritumoral LVI by H&E in comparison to D2–40 IHC (P=.0009). MCCs in which D2–40 IHC detected both intratumoral and peritumoral LVI were typically larger than MCCs without (mean, 24.5mm vs 17.3mm; P=.03) and more frequently metastasized (87% vs. 51%; P=.03). D2–40 IHC detection of both intratumoral and peritumoral LVI is associated with metastasis.



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