Localised pityriasis rosea‐like eruption during radiotherapy. Report of 2 cases

Pityriasis rosea is a common skin condition that presents acutely with asymptomatic, scaly and oval plaques, usually in a well‐recognised distribution over the trunk. Two men developed ovoid, scaly and annular lesions limited to the radiotherapy field during treatment for pelvic malignancies and without a preceding herald patch. Other causes of the eruption were excluded on clinical and pathological grounds and the histopathological features were consistent with a pityriasis rosea‐like eruption. In both cases the lesions resolved spontaneously by 8 weeks. These are the first reported cases of a localised pityriasis rosea‐like eruption arising during radiotherapy.     

Pityriasis rosea-like eruption due to bismuth

We report a case of bismuth-induced pityriasis rosea-like drug eruption. Although historical accounts of bismuth hypersensitivity exist, contemporary reports are lacking. Given the frequency of bismuth administration, a modern review of this phenomenon would seem prudent.     

Pityriasis rubra pilaris‐like reaction induced by imatinib

Imatinib, a kinase inhibitor, is currently approved for the treatment of chronic myeloid leukaemia, gastrointestinal stromal tumours (GIST), and other malignant conditions such as dermatofibrosarcoma protuberans. Treatment with imatinib is generally well tolerated, but some cutaneous adverse events (AEs), such as exanthematous papular eruptions and Stevens–Johnson syndrome have been reported. We report a case of a pityriasis rubra pilaris (PRP)‐like eruption associated with this drug. Although cutaneous AEs associated with imatinib are relatively common (up to 69% of cases), no previous cases of PRP‐like eruptions related to this drug have been described previously, to our knowledge.     

Erythema multiforme‐like eruption localized to a sun‐exposed area

We report on a 35‐year‐old woman with cutaneous lesions characterized by an erythema multiforme‐like appearance localized in the photo‐distributed pattern. She had no history of systemic drug ingestion, herpes simplex virus or any other infection, possible causes of erythema multiforme, before the sun exposure. She had normal tolerance to a phototest, but photoprovocation tests could not be performed because she did not agree to them. This case was diagnosed to be an erythema multiforme‐like variant of a polymorphous light eruption; the differential diagnosis of target‐like lesions in a photo‐distributed pattern is discussed.     

Pemphigus vegetans with paronychia‐like changes resistant to rituximab therapy

Pemphigus vegetans (PVeg) is a clinical variant of pemphigus vulgaris (PV) that makes up about 2% of all cases. It is distinguished from PV by the presence of vegetative plaques that are usually found in the oral mucosa or intertriginous areas. PVeg can present as one of two clinical subtypes: Hallopeau type and Neumann type. The Hallopeau type is a milder form of the disease, often sparing the oral mucosa. The Neumann type is a more severe form that often includes oral mucosal involvement. Nail unit disease of PVeg is rare, lending to limited recommendations for management. Herein, we present a case of PVeg with paronychia‐like changes following rituximab therapy, along with a brief review of PVeg nail unit disease management. Previously reported treatments include prednisone, azathioprine, dapsone, and cyclosporine. In this patient with nail disease, despite rituximab therapy, intralesional triamcinolone acetonide was effective, thereby avoiding the need for additional immunosuppression.     

Follicular mucinosis and mycosis‐fungoides‐like drug eruption due to leuprolide acetate: a case report and review

Leuprolide acetate represents a gonadotropin‐releasing hormone agonist, used as part of the treatment of prostate cancer. We report an unusual case of disseminated urticarial rash following leuprolide injection in a 67‐year‐old man that histopathologically and immunohistochemically resembled mycosis‐fungoides, including the presence of follicular mucinosis and eosinophils in the follicles. This histopathologic pattern has not been previously described as a drug reaction pattern due to leuprolide, and it underscores the importance of correlation with the clinical impression to arrive at a correct diagnosis.     

Use of topical povidone‐iodine resulting in an iododerma‐like eruption

Iododerma is a rare skin eruption that is usually induced by the systemic use of iodide‐containing radiographic contrast medium or treatment with oral potassium iodide therapy. Iododerma has also rarely been reported to occur following topical application of iodine. We herein report the case of a 42‐year‐old male who developed multiple pinpoint pustules on both lower extremities. Three days after the eruption began, the patient started applying topical 10% povidone‐iodine solution to the lesions. During this treatment, the lesions enlarged into multiple 2–9‐cm pus‐filled bullae, limited to the treated areas. Lesional bacterial culture swab and Gram stain were negative. Blood cultures were also negative and the patient's white blood cell count was normal. A punch biopsy specimen revealed pseudoepitheliomatous hyperplasia and dermal‐epidermal separation with epidermal necrosis and underlying abscess formation. A superficial and deep perivascular, interstitial and perifollicular infiltrate containing numerous neutrophils, with abscess formation and eosinophils was also seen. This histology was consistent with iododerma and the patient's lesions involuted following cessation of topical iodine use, leaving only post‐inflammatory hyperpigmentation. In summary, our patient likely had a folliculitis that was then treated with topical povidone‐iodine that led to iododerma. Although it remains possible that the reaction was an unusual contact hypersensitivity response, the ulceration, pseudoepitheliomatous hyperplasia and abscess formation do support an iododerma‐like eruption.