A 64-year-old woman presented with left axillary lymphadenopathy in December 2014. Metastatic infiltrating ductal carcinoma of the left breast and left axillary and pectoral lymph nodes was diagnosed. The tumor was clinical stage III T2N2, estrogen receptor negative, progesterone receptor negative, and HER2 overexpressed.\nShe began treatment in 2015 with triple therapy on February 24, March 17, and April 7: paclitaxel, pertuzumab, and trastuzumab. She also received monotherapy with paclitaxel on March 3, March 10, March 24, and March 31. Following her treatment on April 7, she developed eyelid ptosis and peripheral neuropathy with ataxia that was attributed to paclitaxel.\nMonotherapy with trastuzumab was resumed on May 9, 2015. On June 1, 2015, 3 days after receiving trastuzumab on May 29, 2015, she developed pruritus. She also noted a rash developing on her chest, abdomen, arms, and legs.\nCutaneous examination on June 3, 2015 showed erythematous, distinct and intermingled (in a lacy pattern), linear streaks on her arms (Figs. , ), chest, and abdomen (Fig. ). The morphology of the clinical lesions was a flagellate erythema. Similar linear streaks—both erythematous and hemorrhagic—were also noted on her legs (Figs. , ).\nA skin biopsy from her left arm showed basket-weave orthokeratosis overlying a spongiotic epidermis. There was edema in the dermis with a predominantly lymphocytic inflammatory infiltrate that is present around blood vessels in the papillary dermis. There was exocytosis of small lymphocytes into the overlying epidermis (Fig. ). The pathologic findings were those of a spongiotic dermatitis, compatible with a medication reaction.\nCorrelation of the clinical history, symptoms and findings in concert with the pathologic features observed established the diagnosis of drug-induced flagellate erythema. In this patient, the causative agent was trastuzumab.\nShe was treated systemically with prednisone (60 mg each morning for 3 days, followed by 40 mg each morning for 2 days and 20 mg in the morning for 1 day), and antihistamines for 2 weeks: Fexofenadine 180 mg each morning and diphenhydramine 25 mg each evening. Topical therapy was also initiated: Clobetasol propionate 0.05 % cream twice daily for 10 days and then once daily for 4 days.\nWithin 2 days, the itching had resolved and the skin eruption had nearly cleared. Follow-up examination after 2 weeks, on June 17, 2015, showed complete clearing of the flagellate erythema on her chest, abdomen, and arms. The erythematous hemorrhagic linear streaks on her distal legs were less prominent and asymptomatic.\nThe patient has subsequently had a left breast lumpectomy and complete lymph node dissection. There was no residual carcinoma in the breast and 26 lymph nodes were negative for malignancy. She has also received adjuvant radiation therapy.\nHer oncologist decided that she would need to receive treatment with trastuzumab, every 3 weeks, for 1 year. She has been receiving dexamethasone prior to each trastuzumab treatment to prevent recurrence of the adverse skin event. Neither pruritus nor flagellate erythema has occurred with the subsequent administration of trastuzumab.
A 65-year-old retired male (Fitzpatrick phototype II) previously healthy except for a distant history of basal cell carcinoma presented to our dermatology clinic with a two-day duration of a rash. The lesions were first noticed on his chest, upper extremity and back []. The rash was extremely pruritic resulting in insomnia for the previous 2 nights which went unrelieved despite oral diphenhydramine. Also concerning to him and his wife was the whip like nature of the rash which was somewhat linear and run vertically right down his back in a manner unlikely to be produced by simple excoriation. In addition, he denied reaching for or scratching his back in any manner. Review of systems was negative, and he denied any recent history of travel, similarly sick contacts or recent outdoor contactants or change in body soaps or laundry detergents.\nHe denied any prior history of similar rashes and his past medical history was non-contributory. A detailed exposure history revealed the patient had eaten mushrooms 48 hours ago during dinner at a Chinese cuisine buffet. He admitted to ingesting great quantities of a medley of cooked and raw mushroom including the Shiitake mushroom variety.\nPhysical examination was striking with a truncal dominant but generalized rash in a centripetal distribution (). The lesions consisted of raised, relatively uniform erythematous papulovesicles arranged in linear arrangement. Close-up views [] confirmed the papulo-vesicular nature of the rash with multiple small papules grouped both along the breadth and length of each linear streak within an erythematous background.\nGiven the clinical history and presentation the diagnosis was consistent with a shiitake dermatitis. Flagellate patterns of eruption have also been noted in drug reactions particularly to bleomycin, peplomycin (a bleomycin derivative), docetaxel, adult-onset Still’s disease, and dermatomyositis [].\nThe patient was put on a mid-potency topical steroid (Triamcinolone 0.1% ointment applied to affected areas twice daily). The rash resolved within 1 week. It has been reported that shiitake dermatitis can also resolve spontaneously.