Defining True EGR vs EGR-like Eruption
Sézary syndrome represents the leukemic stage of CTCL, which is defined by the triad of erythroderma; generalized lymphadenopathy; and neoplastic T cells in the skin, lymph nodes, and peripheral blood. It is well known that CTCL can mimic multiple benign and malignant dermatoses. One rare presentation of CTCL is an EGR-like eruption.
Erythema gyratum repens presents as rapidly advancing, erythematous, concentric bands that can be figurate, gyrate, or annular, with a fine trailing edge of scale (wood grain pattern). The diagnosis is based on the characteristic clinical pattern of EGR and by ruling out other mimicking conditions with biopsy.1 Patients with the characteristic clinical pattern but with an alternate underlying dermatosis are described as having an EGR-like eruption rather than true EGR.
True EGR is most often but not always associated with underlying malignancy. Biopsy of true EGR eruptions show nonspecific histopathologic features, with perivascular superficial mononuclear dermatitis, occasional mild spongiosis, and focal parakeratosis; specific features of an alternate dermatosis are lacking.2 In addition to CTCL, EGR-like eruptions have been described in a number of diseases, including systemic lupus erythematosus, erythema annulare centrifugum, bullous dermatosis, erythrokeratodermia variabilis, urticarial vasculitis, leukocytoclastic vasculitis, and neutrophilic dermatoses.
Prior Reports of EGR-like Eruption in Association With MF
According to a PubMed search of articles indexed for MEDLINE using the terms erythema gyratum repens in mycosis fungoides, mycosis fungoides with tinea, and concentric wood grain erythema, there have been 6 other cases of an EGR-like eruption in association with MF (Table). Poonawalla et al3 first described an EGR-like eruption (utilizing the term tinea pseudoimbricata) in a 55-year-old man with stage IB MF (T2N0M0B0). The patient had a preceding history of tinea pedis and tinea corporis that preceded the diagnosis of MF. At the time of MF diagnosis, the patient presented with extensive concentric, gyrate, wood grain, annular lesions. His MF was resistant to topical mechlorethamine, psoralen plus UVA, and oral bexarotene. The body surface area involvement decreased from 60% to less than 1% after institution of oral and topical antifungal therapy. It was postulated that the widespread dermatophytosis that preceded the development of MF may have been the persistent antigen leading to his disease. Preceding the diagnosis of MF, skin scrapings were floridly positive for dermatophyte hyphae. Fungal cultures from the affected areas of skin grew T rubrum.3
Moore et al4 described an EGR-like eruption on the trunk of a 73-year-old man with stage IA MF (T1N0M0B0). Biopsy was consistent with MF, but no fungal organisms were seen. Potassium hydroxide preparation and fungal cultures of the lesions also were negative for organisms. The patient was successfully treated with topical betamethasone.4Jouary et al5 described an EGR-like eruption in a 77-year-old man with stage III erythrodermic MF (T4N1M0B0). Biopsy showed mycelia on PAS stain. Subsequent culture isolated T rubrum. Terbinafine (250 mg/d) and ketoconazole cream 2% daily were initiated and the patient’s EGR-like rash quickly cleared, while MF progressed to SS.5
Cerri et al6 later described a case of EGR-like eruption in a 61-year-old man with stage I MF and an EGR-like eruption. Microscopic examination of potassium hydroxide (KOH) preparations and fungal culture of the lesions failed to demonstrate mycotic infection. There was no mention of PAS stain of skin biopsy specimens. In this case, the authors mentioned that EGR-like lesions preceded exacerbation of MF and questioned the prognostic significance of the EGR-like eruption in relation to MF.6
Holcomb et al7 reported the next case of a 75-year-old man with stage IIB MF (T3N0M0B0) with CD25and CD30 large cell transformation who presented with an EGR-like eruption. In this case, PAS stain and KOH preparations were repeatedly negative for mycotic infection. Disease progression was not mentioned following the appearance of the EGR-like eruption.7
Nagase et al8 most recently described a case of a 73-year-old Japanese man with stage IB (T2N0M0B0) CD4CD8 MF and lung cancer who developed a cutaneous eruption mimicking EGR. Microscopy and culture excluded the presence of a mycotic infection. The patient achieved partial remission with photochemotherapy (psoralen plus UVA) combined with topical corticosteroids. No major changes in the patient’s skin lesions were noted following surgical resection of the lung cancer.8