Epidermis with atypical keratinocytes

Epidermis with Atypical Keratinocytes        See DX Path for details of the conditions below

Be certain they are atypical keratinocytes and not melanocytes , lymphocytes or Paget cells!
If primarily in the lower two thirds of the epidermis then we call these solar keratoses. If full thickness atypia we call these scc in situ.

Bowen's Disease

You may need to do immunoperoxidase studies to determine the true nature of some of these other cells.

There can be clear cell change in keratinocytes due to glycogen in the cells. 

Some variants of Seborrhoeic keratoses can have large cells (large cell acanthoma) clear cells (Clear cell acanthoma) and Clonal seborrhoeic keratosis. Areas of Bowen's disease can occur within seborrhoeic keratoses.

Epidermolytic hyperkeratosis changes can also look atypical as are the changes of warts with koilocytosis.

Verruca Vulgaris