Becoming “sensitized” to the clinical utility of the term “urticarial dermatitis” (a subtype of the dermal hypersensitivity reaction pattern)

By David A. Wetter, MD, FAAD
April 2, 2025
Vol. 7, No. 13

I suspect many of us have been confounded when confronted with a patient presenting with cutaneous findings suggestive of a “dermal hypersensitivity reaction.” What is the cause? How should it be evaluated and treated? What do we tell our patients? In 2002, Maxwell Fung, MD, explored this concept, noting that “dermal hypersensitivity reaction” was not clinically useful and that a better histopathologic term was “dermal hypersensitivity reaction pattern,” which informs clinicians of a distinctive pattern of microscopic findings that can be observed in a variety of pruritic dermatoses with similar clinical features. (1)

In 2006, I saw a patient in my resident community clinic who suffered from a chronic, recalcitrant, pruritic skin eruption. My supervising faculty that day, Gabriel Sciallis, MD, saw the patient with me and said, “I think this patient has ‘urticarial dermatitis,’” highlighting a recent publication from Steven Kossard, MD (an alumnus of our Mayo Clinic Dermatology residency program) that sought to define this new term. (2) Dr. Kossard noted that patients with urticarial dermatitis “present with urticarial plaques and papules that may resemble urticaria, but the individual lesions often last longer than 24 hours and often last for days. The lesions are usually intensely pruritic, and there may be a predominant papular element or urticated erythema with excoriations.” (2) Patients with this clinical presentation were considered to have “urticarial dermatitis” when histopathology of a skin biopsy demonstrated “an upper dermal perivascular and interstitial lymphocytic inflammatory reaction with eosinophils and an overlying epidermis demonstrating minimal spongiosis and a normal stratum corneum.” (2) While recognizing that the clinical presentation of urticarial dermatitis was not specific to a specific entity (although eczema and drug eruptions tended to be the most frequent clinical associations), Dr. Kossard concluded that “urticarial dermatitis” was a useful term for both clinicians and pathologists and that a subset of patients with the aforementioned clinical findings had distinctive histopathology as described above, supporting the concept of “urticarial dermatitis” as a subset of the dermal hypersensitivity reaction pattern. (2)

After the publication of Kossard et al (2), Robert Rietschel, MD, wrote in an editorial that urticarial dermatitis was often unresponsive to topical corticosteroids and phototherapy and that “whatever this disease is to be called, it is poorly understood and by no means rare.” (3) Five years later, in a publication highlighting the commentary by Kossard et al. as a top-accessed article, Michael Tharp, MD, stated that “urticarial dermatitis as a clinical diagnosis represents a reaction pattern with a broad differential diagnosis that includes drug reactions, viral exanthems, infestations, prodromal bullous pemphigoid, dermatitis herpetiformis, pruritic urticarial papules and plaques of pregnancy, dermal contact dermatitis, and even urticarial vasculitis, thus underscoring the importance of a skin biopsy to differentiate among these disorders.” (4) Thus, the differential diagnosis for skin conditions with a predominant urticarial component includes cutaneous diseases (such as urticarial dermatitis) and systemic diseases (including rheumatologic and hematologic conditions). (5, 6)

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Dr. Sciallis’s bedside teaching in 2006 about urticarial dermatitis left an indelible impression, as I continue to see patients with clinical eruptions as described by Kossard et al (2) (and struggle with how to evaluate and treat them). What are the frequencies of final dermatologic diagnoses in patients who initially present with clinical features of urticarial dermatitis? What is the proper workup of these patients (to confirm a final diagnosis of urticarial dermatitis and to exclude the myriad entities in the differential diagnosis)? These questions spurred me (along with Gregory Hannon, MD, and Lawrence Gibson, MD) to explore our experience of 146 patients seen at Mayo Clinic between 2006-2012 with clinical findings of urticarial dermatitis at the time of their initial dermatologic evaluation. I have summarized below some of the pertinent findings of our study (7):

• Of the 146 patients, 60% were women and the median age at disease onset was 61 years.

• The most commonly involved sites were the trunk (91%), lower extremities (75%), and upper extremities (73%).

• 10% of patients required inpatient dermatologic admission due to the severity of their disease.

• Workup for the 146 patients included a skin biopsy (81%), direct immunofluorescence microscopy (68%), complete blood count (73%), cutaneous (indirect) immunofluorescence (34%), immunoglobulin E (20%), patch testing (23%), serum protein electrophoresis (27%), antinuclear antibody (27%), scabies preparation (7%), and tissue transglutaminase antibodies (23%).

• Final diagnoses of the 146 patients with clinical urticarial diagnosis were: urticarial dermatitis (48%); dermatitis not otherwise specified (16%); acute/chronic urticaria (10%); drug reaction (6%); bullous pemphigoid (4%); atopic dermatitis (3%); contact dermatitis (3%); polymorphous eruption of pregnancy (2%); scabies (1%); and other diagnoses (6%) (cutaneous T-cell lymphoma, Schnitzler syndrome, graft-versus-host disease, asteatotic dermatitis, possible hypereosinophilic syndrome, irritant dermatitis, and suspected scabies with response to empiric treatment).

• Of the 70 patients with a final diagnosis of urticarial dermatitis, 53 had biopsy specimens available for review, and 40 of these had histopathologic findings consistent with urticarial dermatitis.

• Characteristics of the 40 patients with clinical and histopathologic urticarial dermatitis included:

  • Median age of 62 years; 62% women

  • Involvement of trunk (90%), lower extremities (82%), upper extremities (75%)

  • 18% required inpatient dermatologic admission.

  • Median duration of disease at diagnosis was 4.9 months.

  • 10% (4 of 40 patients) had diagnosis of malignancy within 4 months of urticarial dermatitis onset (myelodysplastic syndrome concomitantly; colonic tubular adenoma concomitantly; prostate cancer 3 months after; stage 4 vulvar cancer 4 months before).

  • Individual treatments included oral antihistamines; topical corticosteroids; wet dressings with topical corticosteroids (at home or on the inpatient dermatology service); narrowband UVB phototherapy; prednisone; and topical calcineurin inhibitors.

    • In 35 patients with more than 15 days of follow-up, 20% had a complete response to treatment; 34% had a partial response; and 46% had no response to treatment.

Overall, our Mayo Clinic study found that 28% of patients (41 of 146) who initially presented with clinical features of urticarial dermatitis were found to have non-dermatitic diagnoses to account for their findings, highlighting that urticarial dermatitis as a clinical reaction pattern “may be seen in various dermatologic conditions and that diagnostic evaluation is necessary to correlate clinical findings in a given patient.” (7) Those with clinical and histopathologic features of urticarial dermatitis often had disease that was chronic or persistent, as nearly half of the patients with adequate follow-up (16 of 35) had no response to treatment. As 10% of patients (4 of 40) with both clinical and histopathologic features of urticarial dermatitis had a malignancy diagnosed within 4 months of onset of their cutaneous findings, it may be prudent to perform a thorough review of systems and an age-appropriate malignancy workup in patients with recalcitrant urticarial dermatitis or a focused screening in those patients with a concerning review of systems.

One of my former colleagues (and now emeritus professor), Lisa Drage, MD, used to describe psoriasiform dermatitis to patients as a “particularly difficult-to-treat type of eczema.” I think the same can be said of urticarial dermatitis and can help to set expectations for our patients who have this diagnosis. Since urticarial dermatitis may not improve with topical treatments or phototherapy, conventional steroid-sparing immunosuppressive treatments (such as mycophenolate mofetil) may be helpful in my (anecdotal) experience. Dupilumab is increasingly being used in our Mayo Clinic practice to treat urticarial dermatitis and related conditions (8) and I anticipate that reports of Janus kinase inhibitors (such as upadacitinib and abrocitinib) to treat urticarial dermatitis will soon pepper the literature. Matthew Zirwas, MD, also describes an excellent approach to managing patients with urticarial dermatitis based upon available literature and clinical experience. (9)

So why else might the use of the term “urticarial dermatitis” be helpful for clinicians and our patients? Many times, I have evaluated patients with “excoriated dermatitis,” dermatitis not otherwise specified, or another similar chronic pruritic dermatosis that did not reveal a more specific diagnosis despite extensive testing. Even after spending more than an hour with these patients and carefully explaining my diagnosis and management plan, they sometimes remarked, “So what you are saying is that we still don’t know what this is, and we don’t know how to treat it?” Fortunately, for some of these patients, I can confidently give them a final diagnosis of urticarial dermatitis, which gives them a palpable sense of relief at being able to put a name to their condition. In my experience, when I show patients our Mayo Clinic study about urticarial dermatitis and explain to them why I feel their condition fits with this diagnosis (after a comprehensive workup has been completed), it helps to build rapport and trust in our relationship. Patients feel more confident in my treatment recommendations and hopefully are more likely to adhere to them rather than continuing to search for other diagnoses through continued testing. A study performed in a primary care clinic supported these observations, noting that when patients reported receiving information about their symptom diagnosis and prognosis during their clinic visit, that they experienced “greater satisfaction, less worry, fewer unmet expectations, and better 2-week symptom outcomes.” (10)

Point to Remember: Consider using the term “urticarial dermatitis” in your dermatologic practice. This can help guide your diagnostic evaluation, enhance therapeutic relationships, and set expectations for prognosis.

Our expert’s viewpoint

Matthew Zirwas, MD, FAAD
Associate Professor, Ohio University Heritage College of Osteopathic Medicine
DOCS Dermatology
Columbus, Ohio

Urticarial dermatitis remains one of the fascinating dermatologic entities for which we have no solid concept of the underlying pathophysiology. Certainly there are many patients in whom the clinical and histologic findings can be explained by a specific, diagnosable trigger that can be addressed, leading to resolution of the findings — bullous pemphigoid, scabies, etc. However, as Dr. Wetter indicates, in the majority of these patients there is no identifiable underlying cause. My experience is that one of the biggest ‘risks’ these patients face is a prolonged delay in receiving effective therapy while their dermatologist is searching for the underlying cause, which is never found in the majority of patients. This risk is often exacerbated by a dermatopathology report which may state something along the lines that the reaction pattern looks like a reaction to an internal antigen...

I believe the biggest clue we have to the etiology of the urticarial dermatitis in patients with no identifiable etiology is that UD has been triggered in many people by Covid vaccines and by treatment with CTLA-4 antibodies designed to break self-tolerance. In both situations, we have high levels of non-specific inflammation. This, combined with the fact that I’ve never seen a true case of UD without an identifiable trigger in anyone under age 50 (and the vast majority in those over age 60), has made me believe that in many patients it is a manifestation of immunosenescence associated non-specific Type 2 inflammation. I’ve found that low dose methotrexate (5-10 mg/wk), which has been shown to increase activity of T-regulatory cells, and mycophenolate, which inhibits effector T-cells, are the most consistently effective therapies, which supports the idea of non-specific/unregulated T-cell activation as the etiology.

My biggest plea to my colleagues is to start treating these patients with effective therapy, such as very low dose methotrexate, early in their course. There is very little risk associated with such low doses of methotrexate and the benefit to these patients in terms of quality of life can be dramatic. Mycophenolate is my preferred second line option. Dupilumab and JAK inhibitors are reasonable options that I’d expect to work well, but I have not used either due to cost and excellent responses to methotrexate and mycophenolate.

1. Fung MA. The clinical and histopathologic spectrum of “dermal hypersensitivity reactions,” a nonspecific histologic diagnosis that is not very useful in clinical practice, and the concept of a “dermal hypersensitivity reaction pattern.” J Am Acad Dermatol. 2002;47:898-907.

2. Kossard S, Hamann I, Wilkinson B. Defining urticarial dermatitis: A subset of dermal hypersensitivity reaction pattern. Arch Dermatol. 2006;142:29-34.

3. Rietschel RL. A clinician’s view of urticarial dermatitis. Arch Dermatol. 2006;142:932.

4. Tharp MD. Top-accessed article: Defining urticarial dermatitis. Arch Dermatol. 2011;147:1436.

5. Peroni A, Colato C, Schena D, Girolomoni G. Urticarial lesions: If not urticaria, what else? The differential diagnosis of urticaria. Part I. Cutaneous diseases. J Am Acad Dermatol. 2010;62:541-55.

6. Peroni A, Colato C, Zanoni G, Girolomoni G. Urticarial lesions: If not urticaria, what else? The differential diagnosis of urticaria. Part II. Systemic diseases. J Am Acad Dermatol. 2010;62:557-70.

7. Hannon GR, Wetter DA, Gibson LE. Urticarial dermatitis: Clinical features, diagnostic evaluation, and etiologic associations in a series of 146 patients at Mayo Clinic (2006-2012). J Am Acad Dermatol. 2014;70:263-8.

8. Edmonds N, Noland M, Flowers RH. Six cases of refractory pruritus and histologic dermal hypersensitivity reaction successfully treated with dupilumab. JAAD Case Reports. 2022;19:28-33.

9. Zirwas MJ. Urticarial dermatitis. In: Basow DS. UpToDate. Waltham, MA: 2024.

10. Jackson JL. Communication about symptoms in primary care: Impact on patient outcomes. J Altern Complement Med. 2005;11 Suppl 1:S51-6.

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