Benign and malignant collision tumors of melanocytic skin lesions with hemangioma: Dermoscopic and reflectance confocal microscopy features.

BACKGROUND

Though the combination/collision of nevi or lentigo simplex and hemangiomas is frequent, the malignant collision tumor melanoma-hemangioma is exceptional and can sometime clinically simulate a benign collision. To date, a series of collision tumors of hemangiomas associated with either benign or malignant melanocytic skin lesions (MSL) has yet to be studied by non-invasive imaging and clinico-pathologic correlates.

METHODS

We present 10 cases of patients with collision tumors of hemangioma with different MSL including: 2 in situ lentigo-maligna melanoma, 1 invasive melanoma, 5 melanocytic nevi, and 2 lentigo simplex. The clinical aspect along with the dermoscopic and reflectance confocal microscopy (RCM) features is described and compared with histopathologic findings.

RESULTS

Dermoscopic examination allows to recognize a dark ring in malignant collision melanoma-hemangioma and a jelly ring sign in benign collision of nevi/lentigo simplex-hemangioma. These peculiar features were confirmed by RCM and histopathologic findings.

CONCLUSION

Two simple dermoscopic clues confirmed by RCM features can be proposed to help distinguish between benign and malignant collisions tumors.