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