This is a typical presentation for lentigo maligna melanoma (LMM), the head and neck of an elderly person. Lentigo maligna (in situ) rarely invades, but when it does, it is often as a spindle cell tumor, as in this case.
Along the dermal/epidermal junction, cytologically atypical melanocytes are present both singly and in nests. Scattered single cells ascend into the epidermis, but the majority reside at the junction. These melanocytes are large and epithelioid with vesicular nuclei, prominent macronucleoli, and moderately abundant pink cytoplasm. Intracytoplasmic melanin pigment is present, but scant. Within the dermis, atypical melanocytes expand the papillary dermis as single cells with a more spindled morphology. Dermal mitoses are present. An inflammatory infiltrate is minimal. There are scattered pigmented melanophages within the dermis.