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Dermacademy Challenge – Clinical Case #1 – Pr. Marie-Sylvie Doutre
- 30min
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Clinical Presentation
Mrs M, 67, has had pruritus that she says is intolerable for 5 months. She says it appears immediately on the torso and legs after taking showers. She is generally well and does not take any drugs. 2nd generation anti-H1 (levocetirizine) at 1 tab per day then 4 tabs per day alone, then combined with 1st generation anti-H1 (25 mg hydroxyzine in the evening) are ineffective. Her doctor mentions a mental cause, especially as the patient, (who is increasingly inconvenienced by the pruritus and now only takes a shower twice a week), says she has no cutaneous lesions. Paroxetine (20 mg/day) is prescribed, leading to a slight improvement.
A dermatology consultation was requested as the symptoms last more than a year.
Social History
Former secretary, married, no children
Physical Examination
The symptoms described by the patient and the absence of cutaneous lesions orient the diagnosis to aquagenic pruritus.
Laboratory Result
The blood test shows changes in the blood count: erythrocytes: 6.2 T/l, haemoglobin: 17.5 g/dl, hematocrit: 53%. Platelets levels are 510 G/l, leukocytes 11.5 G/l. There is no inflammatory syndrome or metabolic disorders.
Diagnosis
In this patient, the diagnosis is that of aquagenic pruritus revealing polycythemia. This blood disease, evoked based on the haematological anomalies, was confirmed by blood volume measurement (total erythrocyte count: 40 ml/kg), the abdominal ultrasound scan showing splenomegaly and above all the presence of JAK2V617F mutation seen in 80 to 90% of cases of polycythemia.
Management and outcome
Aquagenic pruritus is defined as pruritus located in areas in contact with water, regardless of its temperature, without any visible cutaneous lesions. It is described by patients as an intolerable sensation of pruritus, sometimes burning, stinging, prickling, appearing 5 minutes after contact with water on average, sometimes a few minutes after last contact and lasting from around ten minutes to 1 to 2 hours. It can be found all over the body but not on the palms of the hands or soles of the feet, or face.
Aquagenic pruritus is often idiopathic but an underlying cause must always be looked for such as medicinal treatments, usually synthetic malaria drugs, and more rarely other drugs (bupropion, clomipramine), but it is often caused by polycythemia in most cases. In effect, AP is found in more than 50% of cases of polycythemia, and can occur before it by several months or years, as in our patient’s case. Conversely, polycythemia is observed in around 30% of cases of AP. The impact on quality-of-life is often high.
Other myeloproliferative syndromes (essential thrombocytemia, myelofibrosis) can also be related to AP.
When aquagenic pruritus is related to haematological anomalies (elevated hematocrit and/or haemoglobin), the JAK2V617F mutation must be looked for.
There is no codified treatment in the idiopathic forms. Anti-H1 anti-histamines alone or combined are effective in fewer than half of cases. Phototherapy (UVA and/or UVB) leads to an improvement or remission in around 50% of patients but relapse is almost always occurring within 1 week to 6 months. Other one-off treatments are offered such as leukotriene receptor antagonists, betablockers (propanolol, atenolol), serotonine reuptake inhibitors (fluoxetine, paroxetine), interferon alpha, etc.
For AP related to myeloproliferative syndromes, it is the treatment for the syndrome that is the most effective, especially JAK 2 inhibitors, leading to rapid disappearance of the pruritus in most patients treated.
Teaching points
- The aquagenic pruritus diagnosis is clinical, based on patient questioning in the absence of cutaneous lesions.
- Drug use must be looked for.
- Aquagenic pruritus is often found in myeloproliferative syndromes, most often polycythemia, which sometimes reveals the disease.
- When aquagenic pruritus is idiopathic, various therapies can be offered with variable results.
- When aquagenic pruritus is associated with a myeloproliferative syndrome, treatment of the syndrome with JAK 2 inhibitors in particular, causes it to disappear.
Bibliography
- Siegel FP et al., Aquagenic in polycythemia vera :characteristics and influence on quality of life in 441 patients; Am J Hematol 2013 ;88 :665-9.
- Lelonek E et al., Aquagenic pruritus in polycythemia vera: clinical characteristics; Acta Derm Venereol 2018; 98 :496-500.
- Lelonek E et al., Burden of aquagenic pruritus in polycythemia vera Acta Derm; Venereol 2018; 98 :185-90.
- Le Gall-Ianotto C et al., Clinical characteristics of aquagenic pruritus in patients with myeloproliferative neoplasms; Br J Dermatol 2017; 176 :255-8.
- Millington GWM et al., British Association of dermatologists’ guidelines for the investigation and management of generalized pruritus in adults without an underlying dermatosis; Br J Dermatol 2018; 178 :34-60.
- Langabeer SE., Aquagenic pruritus and the JAK2 V617F mutation; Clin Exp Dermatol 2019 ;44 :e33.
- Koh MG et al., Aquagenic pruritus responding to combined UVA/NBUVB; Photodermatol Photoimmunol Photomed 2009; 25 :169-70.
- Morgado-Carrasco D et al., Resolution of aquagenic pruritus with intermittent combined UVA/NBUVB; Photodermatol Photoimmunol Photomed 2017; 33 :291-2.
- Saini KS et al., Polycythemia vera-associated pruritus and its management ; Eur J Clin Invest 2010; 40 :828-34
