Thank you for your inquiry.
The description you give is one of a papular dermatitis. This is of course a generic term and could refer to a number of different dermatologic conditions. Occasionally atopic dermatitis can appear as a papular dermatitis as can, on occasion, contact dermatitis. However, you more than likely would be able to recognize either of these two conditions. Based on your description, neither appears likely in my opinion. Thus, immediate hypersensitivity skin tests or patch testing would probably be of little help to you.
In addition, of course, there are a number of dermatologic conditions that appear as papules. Recently the term "papular dermatitis" was coined to refer to adults with refractory pruritic papules of unknown cause. In this condition, there is a predilection for these papules to appear on the pelvis, trunk, and proximal extremities. Perhaps this condition has been referred to in the past as subacute prurigo. In this condition, the histologic features are consistent with your description, and consist of a perivascular infiltrate of eosinophils and lymphocytes along with focal spongiosis.
From the above, it is obvious that the differential diagnosis of the dermatitis you describe is quite complex and usually would fall under the purview of a dermatologist rather than an allergist per se. In fact, to my knowledge, you would not find anything in our literature, including our standard texts, that would help you with this disorder.
For this reason, I would usually not personally manage a patient which fit your description, but rather refer them to a dermatologist. I feel that their expertise in this regard would exceed my own. Thus, I am not sure that I can personally be of great help to you in managing this condition.
Because of this, I am going to ask for help from a dermatologist to see if there is a different perspective that could be of help to you. To do this, I am asking Dr. Lisa Beck, who is a Professor in the Department of Dermatology at the University of Rochester Medical Center, to respond to your inquiry. When I hear from Dr. Beck, I will of course forward her response to you.
Thank you again for your inquiry.
Phil Lieberman, M.D.
We received a response from Dr. Lisa Beck. Thank you again for your inquiry.
Phil Lieberman, M.D.
Response from Dr. Lisa Beck:
The differential for that clinical picture (e.g. pruritic erythematous papular dermatitis) is in fact remarkably broad including both nonspecific and specific drug eruption(s), granuloma annulare, pityriasis lichenoides chronica, lymphomatous papulosis, lichen planus, sarcoidosis, papular eczema, CT diseases, etc. The histologic description of “superficial and deep perivascular and interstitial mixed inflammatory cell infiltrate with lymphocytes, histiocytes and eosinophils” makes most dermatitic explanations much less likely as they rarely have a deep infiltrate and typically no histiocytes. This histologic picture is quite nonspecific and consistent with granuloma annulare or a CT disease. No mention was made of epithelial changes which one would expect in contact dermatitis or CT disorders. This is a clear demonstration that one needs to carefully combine an in-depth history (including ROS and drug admin history), complete PE and histopathology (or several biopsies) to narrow down the differential.
Lisa A. Beck, M.D.
Professor of Dermatology
University of Rochester Medical Center