SHORT COMMUNICATION 149
ActaDV ActaDV
Advances in dermatology and venereology Acta Dermato-Venereologica
Pre-emptive Evaluation of Venom Allergy in a Patient with Systemic Mastocytosis
Theo GÜLEN 1 – 3 and Cem AKIN 4
1
Department of Respiratory Medicine and Allergy, K85, Karolinska University Hospital Huddinge, SE-141 86 Stockholm, 2 Department of Medicine Solna, Immunology and Allergy Unit, Karolinska Institutet, 3 Mastocytosis Centre Karolinska, Karolinska University Hospital and Karolinska Institutet, Stockholm, Sweden, and 4 Department of Internal Medicine, and Division of Allergy and Clinical Immunology, University of Michigan Health System, Ann Arbor, Michigan, USA. E-mail: Theo. gulen @ sll. se; Theo. Gulen @ ki. se Accepted Sep 13, 2017; Epub ahead of print Sep 13, 2017
Systemic mastocytosis( SM) is a clonal disorder of mast cells( MCs) characterized by the accumulation and activation of these cells in at least one extracutaneous organ( 1, 2). Anaphylaxis is a well-known feature of SM; in particular, venom allergy represents an increased risk of severe anaphylactic reactions to insect stings in these patients( 3, 4). Although the overall prevalence of venom-induced anaphylaxis( VIA) is approximately 25 % in patients with SM( 4), there is no data available to suggest whether pre-emptive evaluation of venom allergy in patients with mastocytosis can reduce the risk of future episodes of VIA. There are also no consensus recommendations about whether to start venom immunotherapy based on positive blood or skin testing in patients with mastocytosis who have not experienced VIA. We present here an instructive case of indolent SM in a patient who experienced VIA, despite the absence of pre-sensitization to venom.
CASE REPORT
A 75-year-old woman presented with a history of reddish-brown spots on her legs, abdomen and chest. The skin lesions were not itchy, but had increased in size over the years. She had consulted a dermatologist for the first time in 2005 and a skin biopsy was taken. However, she was not informed whether the biopsy findings were consistent with urticaria pigmentosa( UP). She subsequently consulted another dermatologist and a new investigation was initiated due to suspicion of mastocytosis. The patient was referred to a local haematologist where she underwent a bone marrow biopsy. She was then referred to the Mastocytosis Center in Karolinska University Hospital Huddinge.
The patient underwent a comprehensive evaluation at the respiratory medicine and allergy clinic at Karolinska University Hospital Huddinge in May 2010. She had no history of pollen or animal dander-induced allergic symptoms and did not report any symptoms of asthma or allergic rhinitis. She had no known drug or food hypersensitivities. She had been stung by a wasp during the early 1990s, but she had had only a local reaction. Furthermore, she did not report any mast cell mediator-related symptoms, such as palpitations, dizziness, hypotension, or symptoms related to the gastrointestinal system. She had never experienced anaphylaxis or syncopal episodes. Her skin lesions did not urticate on exposure to cold, heat, physical exertion, stress, drugs, or intake of alcohol or food. A skin prick test( SPT) with commercial extracts( ALK- Nordic, Kungsbacka, Sweden) was performed, but did not reveal any immunoglobulin E( IgE) sensitization to pollen, animal dander, dust mites, honeybee or Vespula venoms.
Physical examination was unremarkable, except for reddishbrown pigmented spots on the skin of the patient’ s trunk, abdomen, shoulders and legs. Histopathological evaluation of her bonemarrow biopsy revealed the presence of atypical morphology, with spindle-shaped MCs, and presence of aberrant MCs expressing CD25. The bone marrow aspirate was also positive for KIT D816V mutation and her baseline serum tryptase( sBT) levels were elevated( 30 ng / ml; ref. value < 11.4 ng / ml). No other haematological disorder was found. Therefore, these findings fulfilled the diagnosis of indolent SM with UP and the patient was re-referred to her local hospital.
The patient, however, re-contacted the allergy clinic to report an anaphylactic reaction she had after a wasp sting on her right hand in September 2012. A few minutes after the sting, she had lost consciousness, and by the time the ambulance arrived, the patient was unconscious and had difficulty in maintaining her blood pressure. She was immediately given adrenaline, antihistamines and glucocorticoids and taken to the local hospital. In the emergency room, the patient remained unconscious, with low blood pressure( approximately 70 mmHg systolic), and unresponsive to stimuli. She also had expiratory wheezing. She was given a further 0.5 mg intramuscular( i. m.) adrenaline and intravenous( i. v.) hydration. Her systolic blood pressure then began to increase towards 75 mmHg, but still had expiratory wheezing, generalized urticaria and facial angioedema. Electrocardiography( ECG) revealed an irregular rhythm and sharp ST elevations inferiorly. She was admitted to the intensive care unit( ICU) for further observation and discharged after 24 h. Her tryptase levels were not measured during the anaphylactic episode.
At a follow-up visit in February 2013 a new SPT was undertaken. She now tested 2 +( 5 × 6 mm) for Vespula venom, but negative for honeybee venom. In addition, the specific IgE for wasp was 0.83 kU / l( reference < 0.10 kU / l), but negative for bee venom. Analysis of the venom-specific component revealed rVes5 0.12 kU / l and rVes1 0.94 kU / l( reference values < 0.10 kU / l). Her total IgE level was 15 kU / l and sBT 38 ng / ml. The patient confirmed that she had not had any insect stings between her initial visit in May 2010 and September 2012. In March 2013, venom-specific immunotherapy was started with wasp extract( ALK-Abelló, Horsholm, Denmark) according to a 7-week traditional schedule, in which patient was received incremental, weekly doses of venom extract subcutaneously until a maintenance dose of 100 000 standard quality units( SQ-U / ml) was reached. The achieved maintenance dose( 100,000 SQ-U / ml) was then given every 4 – 6 weeks. Up to June 2017 the patient had not experienced any side-effects during updosing or maintenance treatment, and she had not had any new Hymenoptera stings since September 2012.
DISCUSSION
Although venom allergy represents a particular risk for exceptionally severe anaphylactic sting reactions in patients with mastocytosis, the precise mechanisms behind these reactions have not been fully elucidated. It is possible that the high MC load, reflected by higher levels of sBT, is responsible for this association. This idea is supported by a study showing a linear correlation between sBT levels and risk of severe VIA( 5). However, the majority of the study patients(> 91 %) had normal levels of sBT(< 11.4
This is an open access article under the CC BY-NC license. www. medicaljournals. se / acta Journal Compilation © 2018 Acta Dermato-Venereologica. doi: 10.2340 / 00015555-2793 Acta Derm Venereol 2018; 98: 149 – 150