What are these strange bumps?
A 40-year-old woman with multiple tiny, thin bumps on her upper arms reports they started developing about four years ago. She has never had anything like this before. No one in her family has any similar lesions.
Her primary care doctor told her it was a condition called keratosis pilaris. Her internet research seemed to indicate that it was not keratosis pilaris and she presents for a second opinion.
On examination the lesions were reminiscent of lichen and spiny lotuses; however, the bilateral wide spread occurrence led me to think a biopsy would give more information. She was otherwise healthy.
What is the diagnosis?
Diagnosis: Multiple minute digitate hyperkeratosis (aka spiked hyperkeratosis)
Charles E. Crutchfield III, MD
This is an extremely rare condition. It is reportedly transmitted in an autosomal dominant manner and also sporadically. The condition can also be associated with systemic inflammation and/or malignancy.
In this particular patient, I recommend the use of ammonium lotion twice daily. Because the legions were more mysterious than symptomatic, she was more than happy to receive the correct diagnoses. The plan in the future is to use a topical anesthetic cream and to remove any symptomatic lesions. I also recommended that she contact her primary care physician and initiate a general medical examination appropriate for her age and sex.
“The stratum corneum contains spicules of densely compacted orthokeratin with intervening normal basket weave stratum corneum. These keratotic spicules are not associated with hair follicles. Many arise from finely pointed epidermal elevations. The epidermis is otherwise normal. There is no significant inflammation within the dermis. These findings are most consistent with multiple minute digitate hyperkeratosis (spiked hyperkeratosis). A diagnosis of lichen spinulosus was considered, but no keratotic follicular plugs characteristic of this disorder were noted.”