A rare clinical presentation of mastocytosis in an infant

Introduction

Mastocytosis is a heterogenous group of disorders characterized by increased proliferation and accumulation of clonal mast cells in organs. The disease is categorized into two types: systemic and cutaneous. The second type is confined to the skin and occurs most commonly in children. According to WHO, cutaneous mastocytosis (CM) can be divided into: mastocytoma, maculopapular CM (a monomorphic and polymorphic variant) and diffuse CM [1–3]. Clinical presentation of mastocytosis differs and depends on the specific subtype as well as the age of onset [4, 5]. The maculopapular cutaneous mastocytosis (MPCM) is characterized by the presence of macular and papular eruptions that typically present symmetrically on the body. These eruptions are often accompanied by brown or yellowish-orange plaques and nodules. Diffuse cutaneous mastocytosis, in contrast, is marked by widespread mast cell infiltration throughout the dermis, leading to erythroderma and the formation of bullous lesions, which may be hemorrhagic. Mastocytomas, however, present as single nodular or elevated lesions [1, 6].
Irrespective of the disease subtype, the major criterion refers to the presence of typical skin lesions with Darier’s sign, whereas minor criteria include dermal infiltration of cells with immunotype CD117+ in histological examination of the skin biopsy as well as mutations of the KIT gene in skin lesions [1, 6, 7].
The treatment of the cutaneous mastocytosis aims to reduce the severity of cutaneous and systemic symptoms such as pruritus, blistering, flushing, diarrhea, cramping, which are caused by mast cell mediators. Hence, antihistamine drugs are often used to reduce pruritus and other mediator-related symptoms. Due to an increased risk of anaphylactic reaction in mastocytosis, it is required to educate patients about avoiding triggers of mast cell degranulation and provide them with an epinephrine self-injector [8, 9].

Objective

The aim of this paper is to present the case of cutaneous mastocytosis in a 9-month-old infant resembling impetigo and to discuss to the differential diagnosis of this disorder.

Case report

A 9-month-old girl was admitted to the dermatological department with diffuse erythematous lesions with blisters and erosions. The first lesions appeared on the trunk 4 months before admission with some improvement after 2.5 months. 1 month before hospitalization at the dermatology department the skin lesions deteriorated. Initial diagnosis was impetigo, so the patient was treated with systemic antibiotics – amoxicillin with clavulanic acid at a dose of 40 mg + 5.7 mg/day with no improvement of the skin condition. Clinical examination revealed diffuse erythematous and edematous lesions, as well as blisters and oval erosions partially covered with crust. They were mainly located on the trunk, back and scalp. Pruritus, flushing and blistering were also present. Other characteristic mastocytosis symptoms such as diarrhea, cramping or anaphylaxis were not observed. Additionally, an axillary lymphadenopathy was noticed. There were no deviations in a peripheral blood count, however the levels of tryptase (40.8 μg/l (1–11 μg/l)) and aspartate aminotransferase (AST; 36 U/l (0–32 U/l)) were increased. Skin cultures were taken to exclude a possible bacterial infection, and the results were negative. The skin biopsy revealed acanthotic epidermis with hyperkeratosis, subepidermal blister, and dense dermal infiltrate with CD117+ cells indicating the diagnosis of skin mastocytosis. Oral second-generation H1-blocker (cetirizine) was administered, and an epinephrine auto-injector was prescribed. In order to exclude systemic involvement the patient was hospitalized at the hematology department. Ultrasonography of the abdomen and chest X-ray were performed, and no abnormalities were reported. Based on the clinical presentation and persistent tryptase level of 40.8 μg/l it was decided not to perform the bone marrow biopsy. The patient’s parents were informed about the need of regular follow-up visitis by an interdisciplinary pediatric team to monitor the course of the disease (figs. 1–3).

Discussion

Cutaneous mastocytosis is an uncommon disease which may present a broad spectrum of skin lesions [10].
Furthermore, the diagnosis of cutaneous mastocytosis always requires the exclusion of internal organ involvement, particularly bone marrow, liver, spleen and lymph nodes. Crucial examinations include the peripheral blood count, serum tryptase level, basic biochemical examinations, and abdominal ultrasound [1]. In our case, a normal blood count, basal tryptase level (40 μg/l) and no abnormalities in the additional imaging tests caused the doctors to waive further diagnostics.
This case involved an infant girl who developed diffuse erythematous lesions containing blisters and erosions, which raised the suspicion of bacterial etiology of the disease, specifically, impetigo. It is an infectious skin disease, which occurs with high incidence among children and is manifested as erythematous areas with flaccid blisters formation followed by erosions. The most common causes are Staphylococcus aureus and Streptococcus pyogenes [11–13]. However, in our case the lack of effectiveness of administered antibiotics and presence of physiological flora in a skin culture led doctors to search for another diagnosis.

Conclusions

Our case presents that cutaneous mastocytosis might sometimes resemble bacterial diseases such as impetigo, which is quite common among children. In patients with atypical clinical presentation, skin biopsy is crucial to make an accurate diagnosis. The children diagnosed with cutaneous mastocytosis needs to remain under the care of specialists. Therefore, the importance of interdisciplinary cooperation between dermatologists, hematologists and pediatricians should be emphasized.

Funding

The research was financed from the internal funds of the Dermatology, Paediatric Dermatology and Oncology Clinic, Medical University of Lodz, Poland. Clinic’s statute number: 503/1-064-01/503-11-001.

Ethical approval

Not applicable.

Conflict of interest

The authors declare no conflict of interest.

References