Fig. 1

a Axial CT shows a partly well-defined soft mass in the fossa of left lacrimal sac. b An enhanced CT scan shows marked enhancement. c T1-weighted axial MRI shows an intermediate signal intensity mass. d T2-weighted axial MRI shows a iso-or hyper-signal mass. e Gadolinium-enhanced T1-weighted coronal MRI demonstrates a hyperintense, well-defined enhancing mass, extending into the nasolacrimal duct and anterior ethmoid sinus. f Photomicrography of the lacrimal sac melanoma showing heavy melanin pigmentation produced by tumor cells (hematoxylin-eosin, × 40). g These tumour cells producing higher magnification showing spindle and ovoid shaped tumor cells with inhomogeneous pigment granules (hematoxylin-eosin, × 20). h Immunohistochemical staining with HMB-45 showing positive staining of the tumor cells((immunohistochemical staining, × 40). i The tumour cells showing strong immunoreactivity to melanoma-specific antibody, Melan-A in the immunohistochemical examination. (immunohistochemical staining, × 20)