Tinea corporis is rare in neonates and can occur on any part of the body.13 Morphologically, it can present as scaly annular lesions that are fixed and more persistent. Histologically, there are fungal hyphae and/or yeast in the stratum corneum with spongiotic dermatitis and parakeratosis. Our patient’s lesions were not scaly, and the biopsy demonstrated minimal spongiosis. A periodic acid–Schiff special stain was negative for fungal microorganisms.
Neonatal lupus erythematosus can arise at birth or during the first few weeks of life.16 Morphologically, the skin lesions occur on the scalp, forehead, or neck in a periorbital or malar distribution. They can present as erythematous, annular, scaly patches and plaques. Transplacental transmission of material autoantibodies has been implicated in the etiology, and a complication is infantile heart block. Histologically, a skin biopsy typically shows interface/lichenoid dermatitis. However, our patient’s biopsy did not demonstrate interface changes, and serologically she was negative for autoantibodies.
Viral exanthems are skin eruptions that accompany underlying viral infections.17 Morphologically, patients can present with an erythematous maculopapular rash, sometimes with vesicular, petechial, and urticarial lesions. Laboratory confirmation is made by virus-specific serologies. Histologically, viral exanthems can show a superficial, perivascular, lymphocytic infiltrate in the dermis, with reactive T cells and epidermal spongiosis. Our patient was afebrile and had no known sick contacts. A cytomegalovirus immunohistochemical study on the biopsy was negative, and an Epstein-Barr encoding region in situ hybridization study was negative.
Leukemia cutis is the infiltration of the skin by leukemic cells, most often in conjunction with systemic leukemia.18 In infants and children, the most common leukemia is B-cell acute lymphoblastic leukemia. Morphologically, the skin lesions are characterized by single or multiple violaceous papules, nodules, and plaques. Histologically, there is a perivascular to interstitial infiltrate of atypical mononuclear cells in the dermis and sometimes subcutis. The leukemic cells demonstrate enlarged nuclei with coarse chromatin and prominent nucleoli. Increased mitotic activity may be seen with karyorrhectic debris. Immunohistochemically, the tumor cells can be positive for myeloperoxidase, CD43, CD68, CD34, and CD117.18 Although our patient’s biopsy demonstrated mononuclear cells with karyorrhexis, the cells did not have striking atypia and were negative for blast markers. A recent complete blood cell count on the patient was normal.
Conclusion
We report an unusual case of AEI with mononuclear cells consistent with helper T cells. One must keep these cells in mind when evaluating a biopsy of AEI, as they are benign and not suggestive of an atypical lymphoid infiltrate or leukemia cutis. This will prevent misdiagnosis and ensure that the patient receives appropriate management.