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Metastatic basal cell carcinoma: four case reports, review of literature, and immunohistochemical evaluation.

CONTEXT
Metastatic basal cell carcinoma (BCC) is relatively rare and is seldom considered a complication in the routine treatment and follow-up of patients with BCC. Although multiple studies have tried to distinguish aggressive from nonaggressive BCCs, to our knowledge, no consistent clinical, histopathologic, or immunohistochemical features have yet been reported.


OBJECTIVE
To report 4 cases of metastatic BCCs and to evaluate these in addition to known nonmetastatic BCCs with specific immunostains in an attempt to find distinct morphologic or immunohistochemical patterns that could be helpful in identifying aggressive BCCs.


DESIGN
We reviewed 4 cases of metastatic BCCs and recorded the clinical and morphologic findings. We then searched our archives for 14 cases of BCC that followed the usual nonaggressive course. We evaluated these 18 cases with immunohistochemical stains for Ki-67, p53, and bcl-2.


RESULTS
In metastasizing BCC, Ki-67 staining was slightly higher in metastatic sites than in primary sites (average 63% and 51%, respectively). p53 was expressed in 3 of 4 primary sites and 2 of 4 metastatic sites. Bcl-2 was positive in both primary and metastatic sites in 3 of 4 cases. In the 14 cases of nonaggressive BCC, staining for Ki-67 averaged 38%, p53 was positive in 11 cases, and Bcl-2 staining was noted in 13 cases.


CONCLUSIONS
Overall, in the small sample that we evaluated, the immunohistochemical markers for Ki-67, p53, and Bcl-2 did not distinguish between metastatic and nonaggressive BCCs.