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Clinical and Experimental Dermatology

A rare cause of florid, haemorrhagic blisters in two siblings K. Mahmood and L. Nemazee Dermatology Department, Ipswich Hospital, Ipswich, UK doi: 10.1111/ced.12334

Clinical findings An 8-year-old boy was admitted under the joint care of the paediatricians and maxillofacial surgeons with a 9-day history of a subcutaneous mass. On physical examination, there was a firm, tender, subcutaneous lump, 30 mm in size, with redness and swelling of the overlying skin. There was a central, tense, haemorrhagic blister, which ruptured, leaving an ulcer (Fig. 1a). The submental lymph nodes were tender and enlarged. The patient felt unwell, and had a temperature of 39.6°C, and a heart rate of 122 beats/min. There was no history of preceding trauma. The C-reactive protein level was raised at 23 mg/L (normal < 10 mg/L). A provisional diagnosis of an infected sebaceous cyst was made, and intravenous benzylpenicillin was started. However, there was no improvement after a week on antibiotics, and in the meantime, similar but smaller lesions appeared at the left corner of the patient’s mouth and on the dorsum of his left hand (Fig. 1b). At this point, the patient was referred for a dermatological opinion. The mother reported that 3 days previously, the patient’s elder brother (12 years old) had developed a similar lesion on the finger web between the middle and ring finger of his right hand (Fig. 2b). When the brother was examined, he was found to have firm, non-tender, subcutaneous lumps proximally on the dorsum of his right hand, extending to the forearm in a linear fashion (Fig. 2b). The family lived near a farm and owned a cat, which was reported to have scabs and patchy hair

loss. A clinical diagnosis was made and a diagnostic test performed.

Histological findings No biopsy was taken because of the young age of both patients. Bacterial swabs were negative. Blister fluid was taken from the dorsum of left hand of the younger brother and sent for PCR analysis. What is your diagnosis?

(a)

(b)

Correspondence: Dr Leila Nemazee, Department of Dermatology, Ipswich Hospital, Ipswich, Suffolk IP4 5PD, UK E-mail: [email protected] Conflict of interest: the authors declare that they have no conflicts of interest. Accepted for publication 14 December 2013

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Clinical and Experimental Dermatology (2014) 39, pp658–660

Figure 1 Index patient. (a) A large ulcer on the chin and a

crusted lesion at the left corner of the mouth; (b) a haemorrhagic crust on the dorsum of the left hand.

ª 2014 British Association of Dermatologists

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(a)

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Figure 2 Elder brother. (a) A haemorrhagic blister on the right

hand; (b) subcutaneous lumps on the right forearm.

Diagnosis Cowpox.

Discussion The presence of similar lesions on exposed parts of the body in both brothers at the same time was suggestive of an infective cause. The differential diagnosis included orf, milker’s nodule and cowpox. The skin lesions in these viral infections may be clinically indistinguishable, therefore the contact history gave an important clue towards the diagnosis. Orf is generally seen in farmers, butchers and people in contact with lambs and sheep, which are a common cause of infection. Milker’s nodules are seen in milkers and vets who examine the mouths of animals, and in many cases, develop associated lymphangitis.1 In this case, the children did not have a typical contact history seen with orf or milker’s

ª 2014 British Association of Dermatologists

nodule. Cowpox has its natural reservoir in small rodents, but is commonly transmitted by contact with a domestic cat, and this directed us towards the diagnosis of cowpox. Although a skin biopsy was not taken because of the young age of the patients, the usual histological features of cowpox include marked spongiosis, vacuolization, and eosinophilic inclusions. The dermis generally shows a dense inflammatory cell infiltrate comprising histiocytes and macrophages centrally, with lymphocytes and plasma cells in the periphery. The inflammatory infiltrate may be so florid and of such atypical appearance, with the presence of CD30-positive cells, as to be mistaken for anaplastic large T-cell lymphoma. Blister fluid was taken from the dorsum of the patient’s left hand, and sent for PCR analysis for cowpox virus, which was reported as positive, thus confirming the diagnosis. The index patient’s elder brother also had enlargement of his proximal lymphatic channels in a sporotrichoid fashion. The differential diagnosis of sporotrichoid lesions included sporotrichosis, cutaneous leishmaniasis and atypical mycobacterial infection such as fish-tank granuloma. Sporotrichosis is a fungal infection, and transmission from cats has been reported, similar to cowpox.2 Only 1–2 cases of human cowpox are reported each year in the UK, and only a handful of cases are seen worldwide. A side-effect of the widespread vaccination programmes against smallpox and its eradication in 1979 has been decreasing immunity to other pox viruses, and we are now seeing increasing cases of cowpox in rodents and humans. Humans usually acquire cowpox from cats via a break in the skin. The lesion starts with a painful papule, which then rapidly becomes vesicular and haemorrhagic. It ulcerates during the second week, and develops a hard, black eschar.3 Systemic symptoms such as fever and malaise ensue, but usually resolve during the eschar stage. The distribution of lesions is characteristic, and originates on the face, hands or arms, and spread centrally. Lymphangitis is common.4 PCR can be carried out on the lesional fluid, and if positive, confirms the diagnosis, as in our case. Cowpox is a self-resolving condition, and no specific treatment is necessary. The only sequelae are scars at the site of the pox lesions, which occur 4–8 weeks after resolution of the lesions.

Clinical and Experimental Dermatology (2014) 39, pp658–660

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References Learning points

• Worldwide eradication of smallpox in 1979, has resulted in decreasing immunity to cowpox and other pox viruses. • Despite the name ‘cowpox’, cats are the main culprit for transmitting the virus, and small rodents are its natural reservoir. • Obtaining a thorough contact history is key to narrowing down the differential diagnoses.

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1 Nagington J, Tee GH, Smith JS. Milker’s nodule virus infections in Dorset and their similarity to orf. Nature 1965; 208: 505–7. 2 Bustamante B, Campos PE. Endemic sporotrichosis. Curr Opin Infect Dis 2001; 14: 145–9. 3 Laurance B. Cowpox in man. And its relationship with milker’s nodules. Lancet 1995; 265: 764–6. 4 Motley RJ, Holt PJ. Cowpox presenting with sporotrichoid spread: a case report. Br J Dermatol 1990; 122: 705–8.

ª 2014 British Association of Dermatologists

A rare cause of florid, haemorrhagic blisters in two siblings.

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