HISTORY:
A 20+ year-old man presents for evaluation of a scaly red eruption on the right upper extremity and right side of the torso, present for only 6 months. The eruption is described as red, scaly, flaky, itchy, painful, and bleeding. He has tried topical steroids without improvement. He was treated with prednisone, which reportedly “dried out” the lesions. He has no prior history of psoriasis and no history of arthritis. Family history is negative for psoriasis. No history of biologics. Medical history significant for anxiety and depressed mood/depression.
Two biopsies, bacterial and viral cultures were performed
QUESTION:
Based on the following photos, this rash is in what distribution?
- Linear
- Blaschkoid
- Dermatomal
- Koebner
Click to view enlarged photo.
ANSWER
B. Blaschkoid
PATHOLOGY
The biopsies both showed similar features: subacute spongiotic dermatitis. PAS-D stain was negative as were HSV-1, HSV-2 and VZV stains. A wound culture grew out Staph aureus (likely secondarily infected) and the viral culture came back negative.
CASE SUMMARY
The clinical presentation is much more dramatic than what the histology shows. The histology is nonspecific. The clinical presentation favors acquired blaschkoid dermatitis.
Acquired blaschkoid dermatitis is a rare skin condition of unknown cause, first described in 1990 by Grosshans and Marot in Bordex, France. It is also known as Blaschkitis, or idiopathic dermatitis along the lines of Blaschko. It may represent the adult form of lichen striatus. Skin biopsy will show nonspecific spongiotic dermatitis. The deep eccrine inflammation seen in lichen striatus may not be present, as is the case in this patient.
The striking clinical presentation along with this pathology fits best with blaschkoid dermatitis, so named as the papulovesicles follows the “lines of Blaschko.” These lines are thought to represent the embryologic migration of ectoderm, forming straight lines down the upper and lower extremities, a V-shape over the spine, and an S-shape across the torso as seen in these photos. There was strict demarcation of the midline. This condition may resolve within weeks to months, but this patient was treated for symptoms with topical steroids and an antibiotic for the secondary infection
FOLLOW-UP
The patient was started on Valtrex due to the vesicular nature of the rash, as well as Doxycycline. He denied any improvement of rash previously with steroid so he was instructed to discontinue use of topical steroids. The patient is a student several hours away from clinic and was referred to a location closer to where he lives for follow up care.
By: Dr. K. Mireille Chae, MD; Dr. Ashley Dietrich, MD; and Ms. Brooke Moss, PA-C