DOI: 10.7241/ourd.20122.22                                                                         article in PDF
Our Dermatol Online. 2012; 3(2): 112-114
Date of submission: 09.01.2012 / acceptance: 13.01.2012
Conflicts of interest: None



Beatriz Di Martino Ortiz, Liz Lezcano, Mirtha Rodríguez Masi, Oilda Knopfelmacher, Lourdes Bolla de Lezcano

Clinicas Hospital. Faculty of Medical Sciences. National University. Asunción-Paraguay

Corresponding author: Dr. Beatriz Di Martino Ortiz    e-mail: beatrizdimartino@gmail.com


Prurigo is a chronic pruritic papular dermatitis. It is a benign condition, acute or chronic. It is more frequent in spring and summer, affecting patients with a low socio-economic status.
Świerzbiączka jest przewlekłą swędzącą grudkową dematozą. Może mieć łagodny, ostry lub przewlekły przebieg. Występuje częściej w okresie wiosenno-letnim, głównie wśród osób o niskim statusie socjoekonomicznym.
Key words: prurigo; insect bites; itching
Słowa klucze: świerzbiączka; ugryzienie owada; świąd


Prurigo is a syndrome characterized by papular lesions and itching, with an acute or chronic evolution, relatively easy to diagnose by clinical history. Its pathogenesis is due to multiple causes such as insect bites, foci of infection, parasites, etc. It is simple to diagnose and treat but it may have atypical clinical presentation.
Case Report
67-year-old white male, gardener, with a history of asthma. He presented an injury of two weeks of evolution in the left armpit, not related to trauma or insect bites, painful and itchy, crusty and with purulent discharge. Physical examination: erithemato-violaceous nodules, 2 to 5 cm. in diameter with central erosion covered with blackish crust and purulent discharge, which follow a linear path in the left axillary region (Fig. 1). No regional lymphadenopathy. Histopathology: epidermal acanthosis, foci of parakeratosis, hypergranulosis and mild spongiosis. Superficial and deep inflammatory infiltrate of mononuclear cells and numerous eosinophils (Fig. 2, 3). The infiltrate reaches the hypodermis. The direct mycological examination and culture of discharge and scaling of lesions was negative for fungi. Routine laboratory normal. With the diagnosis of atopic prurigo the patient was treated with topical betamethasone dipropionate 0.064 gr. + 0.1 g gentamicin, and cephalexin 500 mg. VO, for 10 days. The therapeutic response was favorable with complete remission of lesions a month after starting the specific treatment (Fig. 4).
Figure 1. Clinic. Rounded nodules with central erosion covered with blackish crust and purulent discharge, which follow a linear path in left axillary region
Figure 2. Histopathology. Epidermis with acanthosis, hypergranulosis and focal parakeratosis. Mild spongiosis
Figure 3. Histopathology. Papillary dermis with mononuclear inflammatory infiltrate and numerous eosinophils
Figure 4. Clinical evolution. Complete remission of lesions after a month of treatment
Prurigo is a disease whose elemental lesion is the papule and the primary symptom is itching [1,2]. It is a reaction that usually affects male (3:1) children aged 1 to 7 years, without racial preference. Predominates in tropical countries, like ours, during the warmer months and is seen mainly in lower socioeconomic status [3]. The lesions are caused by insect bites. The most frequently involved are: Cemex lectularius (bedbug) and Pulex Irritians (fleas). Other ectoparasites involved may be flies, trombidias, tung and ticks [3,4]. Early lesions of prurigo by insect are due to a type I hypersensitivity response caused by the release of IgE that is clinically manifested by rash, later involving in a type 4 hypersensitivity mechanism, dependent on T lymphocytes, which causes late lesions causing papules [5]. Three phases are described in terms of response mounted to the sting of an insect: at first the person is unresponsive to the bite for lack of awareness, and after a history of previous bites and response there has started an awareness, and finally, in adulthood desensitization is established after many bites. In some ways this may explain why children under one year have not been exposed, hardly react to insect bites, one case presented hemorrhagic macula showing the location of the lesion and is clearly secondary to trauma and almost always asymptomatic, whereas in the period between 2 and 7 years desensitization occurs following the bites being more common so the insect prurigo at this age, much less common in adults [3].
Classification [4]:
– Scrofula or Prurigo of Children: Common between the first and second year of life, caused by a hypersensitivity reaction to insect bites toxins. It is manifested by sudden onset of hives in the middle and papules over tiny vesicles accompanied by itching.
– Prurigo Simple: common in adolescents and adults, also produced by a hypersensitivity reaction to various causes such as insect bites, light, hormonal disorders, pregnancy, oral contraceptives, and so on. Clinically it is similar to Scrofula.
– Prurigo Eczema: in adults, may be in the form of atopic eczema, manifesting as lichenified plaques quickly, accompanied by intense and persistent itching.
– Nodular Prurigo (Hyde): chronic condition of unknown etiology but different states may induce their appearance, for example, internal diseases, kidney failure or psychiatric disorders, AIDS, Hepatitis C, mycobacteria, Helicobacter pylori, Strongyloides stercoralis [2,7,8]. It is characterized by papulo-nodular lesions 0.5 to 3 cm. in diameter, with abrasions on the surface, with intense itching with chronic and no tendency to regression.
The initial lesion is a wheal acute prurigo, often crowned by a central dark spot or a blister. After several hours papules form firm, glossy, 3 to 10 millimeters in diameter, grouped, symmetrical distribution and very itchy. They may be excoriated, lichenified, or overinfected with crusting on the surface. The lesions recur in outbreaks of between 10 and 20 injuries, and are in various stages of evolution. Most of the lesions persist between 2 and 10 days with red or redness persists or postinflammatory pigmentation after resolution. Eventually, scar tissue can develop. The acute prurigo is not associated with systemic symptoms or lymphadenopathy or lymph neighbors [5]. Lesions that are covered parts suggest bedbugs or fleas, which are not covered in parts, flying insects such as mosquitoes or flies. The usual complications are contact dermatitis and impetigo [3]. Sensitized patients may have a generalized rash to be bitten again to reactivate the previously affected areas. The evolution of disease outbreaks is irregular intervals with changes in environment [5]. The differential diagnosis of scabies should be made, acropapulosis of childhood chickenpox and atopic dermatitis [1]. For diagnosis, biopsy is not required. In the epidermis there is spongiosis or intercellular edema, epidermal necrosis can be found, sometimes there are real blisters. The dermis is infiltrated by lymphocytes, histiocytes, and many eosinophils. Many times the small nerves are thickened [3].
Treatment of prurigo is based on [6]:
General measures:
– Explain to patients the natural history of disease, atopic predisposition, age of onset, chronicity and evolution is fundamental.
– Recommend use of pajamas with long sleeves and pants, close windows and placing mosquito netting when sleeping, and avoid animals or plants within the sleeping quarters.
– Use of insecticides regularly with preventive measures. Topical measures:
– Steroids for three or four days in early stages of the disease to reduce the itching and blistering.
– Pasta and creams inherent drying.
– Solutions with menthol, phenol or camphor.
– If infection were administered aggregate an antiseptic or antibiotic ointment. Systemic actions:
– Antihistamines such as hydroxyzine (1mg/kg/day), chlorpheniramine or other non-sedating.
– Thiamine excretion VO which prevents the skin from insect bites (200 and 600mg/day).
– Intravenous immunoglobulins for atopic prurigo nodularis [9].
– Narrowband UVB phototherapy [10].
We present the case for the unusual clinical presentation in an adult patient (bulky lesions showed a rare anatomical site), having to resort to auxiliary diagnostic methods, and the satisfactory therapeutic response.
1. Calderon Rivera JS, Rosas Vargas MA, Mejia SA, Alcon Moncada AM, Navarro River BE, Monge Sienrra GG: Uncommon Manifestations of atopic dermatitis. Alereg Rev Mex. 2007; 54: 96-103.
2. Lee MR, Schumacker S: Prurigo nodularis: a review. Austral J Dermatol. 2005; 46: 211-218.
3. Gómez A, Umana A, Trespalacios AA: Immune responses to isolated human skin antigens in actinic prurigo. Med Sci Monit. 2006; 12: 106-113.
4. Sampaio SAP; Prurigo. In: Sampaio-Rivitti (Eds). Dermatology. 2nd edition, San Paulo: Medical Arts Ltd., 2000.
5. Sakurai Y, Matsui H, Izaki S, Kitamura K: Grouping prurigo: report of cases. J Dermatol. 2001; 28: 75-80.
6. Wong SS, Goh CL; Double-blind, right / left comparison of calcipotriol ointment and betamethasone ointment in the Treatment of Prurigo nodularis. Arch Dermatol. June 2000; 136: 807-808.
7. Savoia F, Casadio C, Tabanelli M, Gaddoni G, Savoia F, Patrizi A, et al: Prurigo nodularis as the first manifestation of a chronic autoimmune cholestatic hepatitis. Int J Dermatol 2011; 50: 1588-1589.
8. Weisshaar E, Ständer S: Prurigo nodularis in hepatitis C infection: Result of an occupational disease? Acta Derm Venereol. 2011. doi: 10.2340/00015555-1209. [Epub ahead of print].
9. Feldmeyer L, Werner S, Kamarashev J, French LE, Hofbauer GF: Atopic prurigo nodularis responds to intravenous immunoglobulins. Br J Dermatol 2012; 166: 461-462.
10. Jang MS, Baek JW, Kang DY, Kang JS, Kim ST, Suh KS; Successful treatment with narrowband UVB phototherapy in prurigo pigmentosa associated with pregnancy Eur J Dermatol 2011; 21: 634-635.



Other Resources

Our Dermatology Online

Current Issue
All Issues
Instruction for authors
Submit Manuscripts
Ethics in Publishing
For Reviewers
Editors & Publishers 
Contact Us