Abstract

We report a case of a 76-year-old woman presenting with a long-standing asymptomatic erythematous-brownish reticular rash on the back and glutes. After thorough medical history and examination, the patient recognized she lived in a rural area and admitted to sitting with her back to the chimney for long periods of time. Erythema Ab Igne was suspected, and a biopsy was performed to rule out other conditions. We hope exposure to this paradigmatic clinical image may aid in the differential diagnosis of reticular rashes.

Keywords: Erythema Ab Igne; Clinical diagnosis; Dermatology; Pathology.

Abbreviations: EAI: Erythema Ab Igne.

Citation: García-Rodríguez V, Martin-Poch A, Romero-Romero S, Pintiado-Gàmez M, Fernández-Velasco M, et al. Heat’s mark: Unraveling erythema ab igne. J Clin Images Med Case Rep. 2024; 5(6): 3092.

Introduction

Erythema Ab Igne (EAI) is a long-known dermatological entity characterized by a reticular rash related to long-term heat exposure insufficient to cause burn. We present a clinico-pathological case of EAI. Follow-up is recommended in these patients owing to the presumable cutaneous malignancy which can appear thereon.

Case presentation

A 76-year-old woman presented an asymptomatic, erythematous-brownish reticular rash on the posterior aspect of the trunk, arms and glutes (Figure 1). After thorough medical inquiry, the patient admitted to sitting with her back to the chimney for long periods of time. Histopathology revealed prominent dermal angiogenesis, extravasation of red blood cells and mild perivascular lymphocytic infiltrate. The epidermis showed dysmaturative changes, focal vacuolar degeneration, and hyperkeratosis. These changes confirmed the diagnosis of EAI (Figure 2).

Figure 1: Erythematous-brownish reticular rash on the posterior aspect of the trunk, arms and glutes. Several erosions can be noted on the gluteal area bilaterally.

Figure 2: Hematoxylin-eosin stain 40x. Hyperkeratosis, focal vacuolar degeneration and dysmaturative changes. Prominent dermal angiogenesis with red blood cells extravasation and a mild perivascular lymphocytic infiltrate.

Discussion

EAI is allegedly caused by prolonged cumulative exposure to infrared radiation coming from heat sources, not reaching the threshold for burning [1]. EAI has long been recognized, especially in patients using stoves, and can manifest anywhere on the body surface. Nowadays, locations related to modern heat sources such as laptops and cellphones have been described [2]. Clinical suspicion is key, but histopathological evaluation may help rule out other disorders [3]. EAI can seldom lead to squamous cell carcinoma, Merkel carcinoma, and marginal zone B-cell lymphoma [4]. Differential diagnoses include livedo reticularis and racemosa (and all the diagnostic possibilities thereof), poikiloderma and lymphoma. Removal of the heat source is the mainstay of treatment. Dyschromia might improve with laser therapy, depigmentation therapies or topical retinoids, albeit usually permanent.

Conclusion

Medical history itself continues to be crucial in a myriad of dermatological conditions, such as EAI. Histopathology may aid in the differential diagnosis or to rule out complications in doubtful cases. Avoidance of the heat source and follow-up are recommended.

Declarations

Acknowledgments: none.

Funding sources: none.

Ethics statement: written informed consent was obtained from the patient.

Conflict of interest: authors declare no conflict of interests for this article.

References

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