Case 4 Male, 28 years. Papule, bridge of noseShow diagnosis & comments
Spitz tumour of uncertain malignant potential (STUMP)
The overall architecture is very regular; the cell type is consistent with Spitz naevus, but the lesion is rather densely cellular in deeper parts and mitotic figures were easily identified in the dermis, and some were located in the deepest part. This finding ware regarded as supeicious and precluded a confident diagnosis of Spitz naevus.
STUMP (Spitz tumour of uncertain malignant potential) is not a diagnosis, but it conveys the message that the examination of the histological features has not resulted in a confident diagnosis of Spitz naevus or (spitzoid) melanoma. This situation can result from many causes, including suboptimal incomplete biopsy, or histological findings that raise suspicion but not to a degree that the diagnosis of melanoma can be made. In view of the clinical consequences, it is advisable that, before arriving at a verdict of STUMP, the case is referred to a pathologist with a special interest and experience in the diagnosis of spitzoid neoplasms.