Abstract

Multiple minute digitate hyperkeratosis (MMDH) is a rare disorder of keratinization with only 38 prior cases described worldwide. Both an acquired form and an inherited form have been documented. Here, we present a 56 year old woman with a history of breast cancer who developed numerous tiny keratotic spikes on the right arm, bilateral chest, and lateral back that appeared shortly after a recurrence of her breast cancer. On histology, there was digitated compact hyperkeratosis on top of a tented/pointed epidermis, consistent with MMDH. Given the contemporaneous appearance of her MMDH with her cancer recurrence, this likely represents a paraneoplastic phenomenon. This is the second ever case documenting paraneoplastic MMDH, and the first in breast cancer. Dermatopathologists should be aware that MMDH can represent a paraneoplastic phenomenon and to alert the clinician that further work-up for malignancy may be warranted.