Confluent and Reticulated Papillomatosis

The patient is a 21 yo man with a six month history of subtle scaly patches on both axillae.  He was treated by is internist with ketoconazole cream without effect.  A KOH prep was done and was negative.

Clinical Image:

Patches are slightly yellowish and there are islands of sparing.


Pathology: Hyperkeratosis, papillomatosis (increased compared to specimen B), mild epidermal hyperplasia and a superficial perivascular lymphocytic infiltrate consistent with confluent and reticulated papillomatosis.
NOTE: The differential diagnosis could include acanthosis nigricans. PAS stain is negative for fungal organisms.
Photomicrographs courtesy of Jonathan Ho MD MS, Department of Dermatopathology, Boston University School of Medicine

Diagnosis: confluent and reticulated papillomatosis.

This is a difficult diagnosis clinically and histologically.  It's  a type of "dermatological non-disease."  Without the help of an experienced dermatopathologist I doubt that this diagnosis would have been arrived at.

The patient will be treated with minocycline, 100 mg bid for a month.  If this is CARP the process will be resolved.