Annular erythemas of infancy (AEIs) are rare benign skin eruptions characterized by annular or circinate, erythematous patches and plaques that arise in patients younger than 1 year.1 Annular erythemas of infancy originally were described by Peterson and Jarratt2 in 1981. Relatively few cases of AEIs have been reported in the literature (eTable).2-15
Case Report
An 11-month-old girl presented to dermatology for a rash characterized by annular erythematous patches and plaques on the back, arms, and legs (Figure 1). Three months prior, the rash was more diffuse, monomorphic, and papular. Based on physical examination, the differential diagnosis included a gyrate erythema such as erythema annulare centrifugum (EAC), neonatal lupus, a viral exanthem, leukemia cutis, and AEI. A skin punch biopsy was performed.
FIGURE 1. A, An 11-month-old girl with annular erythematous patches and plaques on the back. B, Annular erythematous lesions were present on the right arm, from which a punch biopsy was taken.
Histologically, the biopsy revealed a superficial to mid dermal, tight, coat sleeve–like, perivascular lymphohistiocytic infiltrate admixed with rare neutrophils in eosinophils within the dermis (Figure 2A). The infiltrate also contained numerous large mononuclear cells with enlarged nuclei, fine loose chromatin, rare nucleoli, and a thin rim of cytoplasm (Figure 2B). There were associated apoptotic bodies with karyorrhectic debris. Immunohistochemistry exhibited enlarged cells that were strong staining with CD3 and CD4, which was consistent with reactive helper T cells (Figure 3). A myeloperoxidase stain highlighted few neutrophils. Stains for terminal deoxynucleotidyl transferase, CD1a, CD117, and CD34 were negative. These findings along with the clinical presentation yielded a diagnosis of AEI with reactive helper T cells.
FIGURE 2. Histopathology demonstrated annular erythema of infancy with mononuclear cells. A, There was a superficial to mid dermal, tight, coat sleeve–like, perivascular, lymphohistiocytic infiltrate admixed with rare neutrophils in eosinophils within the dermis (H&E, original magnification ×40). B, The infiltrate contained numerous large mononuclear cells with enlarged nuclei, fine loose chromatin, rare nucleoli, and a thin rim of cytoplasm (H&E, original magnification ×400).
Comment
Clinical Presentation of AEIs—Annular erythemas of infancy are rare benign skin eruptions that develop in the first few months of life.1,16 Few cases have been reported (eTable). Clinically, AEIs are characterized by annular or circinate, erythematous patches and plaques. They can occur on the face, trunk, and extremities, and they completely resolve by 1 year of age in most cases. One case was reported to persist in a patient from birth until 15 years of age.9 It is thought that AEIs may occur as a hypersensitivity reaction to an unrecognized antigen.
FIGURE 3. A, Immunohistochemistry revealed the infiltrate was composed predominantly of CD3+ T lymphocytes (original magnification ×100). B, The enlarged cells were CD4+, consistent with reactive helper T cells (original magnification ×400).
Histopathology—Histologically, AEIs demonstrate a superficial and deep, perivascular, inflammatory infiltrate in the dermis composed of small lymphocytes, some neutrophils, and eosinophils.16 Less common variants of AEI include eosinophilic annular erythema, characterized by a diffuse dermal infiltrate of eosinophils and some lymphocytes, and neutrophilic figurate erythema of infancy, characterized by a dermal infiltrate with neutrophils and leukocytoclasis without vasculitis.1
Our patient’s skin rash was unusual in that the biopsy demonstrated few neutrophils, rare eosinophils, and larger mononuclear cells consistent with reactive helper T lymphocytes. Although these cells may raise concern for an atypical lymphoid infiltrate, recognition of areas with more conventional histopathology of AEIs can facilitate the correct diagnosis.
Differential Diagnosis—The main considerations in the differential diagnosis for AEIs include the following: EAC, familial annular erythema, erythema gyratum atrophicans transiens neonatale, erythema chronicum migrans, urticaria, tinea corporis, neonatal lupus erythematosus, viral exanthems, and leukemia cutis.16