Mastocytosis is a rare disease characterized by clonal proliferation of mast cells that accumulate in various body tissues and organs. Its classification comprises cutaneous and systemic forms.1 Imatinib is an oral tyrosine kinase inhibitor approved for treatment of systemic mastocytosis (assuming the presence of KIT D816V mutation was excluded or its status is unknown).

A 47-year-old woman with indolent systemic mastocytosis (KIT D816V-negative) confirmed by bone marrow trephine biopsy (taken because she had multiple unexplained vertebral compression fractures) was admitted to a hospital due to erythematous lesions on the hands and feet. Furthermore, the patient reported pain in the small joints of the hands and feet, as well as itching and tightness of the throat. She was treated with oral imatinib (600 mg per day) for 3 weeks due to a suspicion of clinically advanced mastocytosis (there was no other explanation for vertebral fractures at that time). An adverse drug reaction to imatinib was initially considered. A hematologist stopped imatinib and introduced 20 mg of oral prednisone per day.

As the skin lesions persisted for 10 consecutive days, the patient was consulted by a dermatologist. Symmetrical erythematous, edematous plaques and peripheral papules were found on the palms and dorsal surfaces of the hands and feet, accompanied by swelling of the wrists and ankles. Additionally, there were follicular eruptions on the lower extremities, forearms, and elbows (Figure 1A–1C). The dose of prednisone was increased to 40 mg per day for 1 week and additional laboratory tests were ordered.

Figure 1. A–C – initial skin lesions: erythematous, edematous plaques and peripheral papules, localized symmetrically on the palms and dorsal surfaces of the hands; follicular eruptions on lower extremities; D–F – visible improvement with reduction of edema and flattening of the skin lesions

Tryptase concentration was 18 µg/l (reference range [RR], 0–11.4 µg/l) and the activity of alkaline phosphatase was 127 U/l (RR, 35–104 U/l). Antinuclear antibodies were negative and the concentration of the C3c complement component was 0.86 g/l (RR, 0.9–1.8 g/l). Serologic tests for hepatitis B virus, cytomegalovirus, and Epstein–Barr virus were negative. The virus antibody panel showed positive results for parvovirus B19 with elevated concentrations of immunoglobulin (Ig) G (88.5 IU/ml; RR <⁠4 IU/ml) and IgM (2083 IU/ml; RR <⁠0.8 IU/ml) antibodies.

At follow-up visits (after 1 and 3 weeks), the patient demonstrated flattening of the skin lesions, reduced swelling, and postinflammatory exfoliation (Figure 1D–1F).

Taking into account the clinical presentation and results of the auxiliary tests, a diagnosis of papular-purpuric “gloves and socks” syndrome (PPGSS) was made. The patient continued treatment of mastocytosis with imatinib at a previous dose.

PPGSS is acute acral dermatosis that occurs primarily in individuals aged 20 to 40 years. Its course is self-limiting and requires only symptomatic treatment.2 This syndrome is typically associated with parvovirus B19 infection.3 The clinical presentation includes painful edema of the small joints of the hands and feet accompanied by pruritic erythematous papules with subsequent petechiae of “gloves and socks” distribution. Small ulcerations of the oral mucosa might coexist.3 Laboratory test results are usually within normal ranges. In immunocompromised patients, PPGSS might be complicated by aplastic anemia, leukopenia,2 and thrombocytopenia.4 Hypothetically, imatinib treatment could be a trigger for parvovirus B19 reactivation; however, a high titer of IgM antibodies suggests a primary infection that caused PPGSS.

This case highlights the need for a careful differential diagnosis of skin lesions initially suspected of being an adverse drug reaction to imatinib. Such eruptions might be observed in 10% to 90% of patients (depending on the imatinib dose).5