Merkel cell carcinoma: histologic features and prognosis.
BACKGROUND
Currently, little is known regarding the potential prognostic value of histologic features in primary cutaneous neuroendocrine (Merkel cell) carcinomas (MCC).


METHODS
In a retrospective review of the tumor histology and clinical outcome data (median follow-up, 51 months; range, 3-224 months) of 156 patients with a diagnosis of MCC, the following histologic features were evaluated: tumor thickness, tumor size (greatest dimension of the tumor), microanatomic compartment involved by tumor (dermis and/or subcutis and/or deeper), tumor growth pattern (nodular circumscribed vs infiltrative), lymphovascular invasion (LVI), tumor-infiltrating lymphocytes, tumor necrosis, ulceration, and solar elastosis.


RESULTS
The overall 5-year survival rate was 67.5%. On univariate analysis, parameters that were associated significantly with survival were tumor thickness (P= .001), tumor size (P= .0002), deepest anatomic compartment involved by tumor (P= .0003), tumor growth pattern (P= .003), LVI (P< .00001), tumor-infiltrating lymphocytes (P= .05), and solar elastosis (P= .04). On multivariate analysis, the presence of a nodular growth pattern, low tumor depth, and absence of LVI were associated with longer survival.


CONCLUSIONS
In addition to the known prognostic value of tumor stage, 3 histologic features were identified to have prognostic significance: tumor thickness (depth of tumor invasion), the presence of LVI, and tumor growth pattern.
Andea
Aleodor A
AA
Department of Pathology, Memorial Sloan- Kettering Cancer Center, New York, New York, USA. aandea@uab.edu
Coit
Daniel G
DG
Amin
Bijal
B
Busam
Klaus J
KJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015266:Carcinoma, Merkel Cell / Q000473:pathology*; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D016246:Lymphocytes, Tumor-Infiltrating / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000473:pathology*; D015996:Survival Rate