Massive skin necrosis in Rocky Mountain spotted fever

Cutaneous manifestations of spotted fever rickettsial infections in the Central Province of Sri Lanka: a descriptive study

BACKGROUND

Characteristic skin lesions play a key role in clinical diagnosis of spotted fever group rickettsioses and this study describes these cutaneous manifestations along with basic histological features.

METHODS AND FINDINGS

Study was conducted at Medical Unit, Teaching Hospital, Peradeniya, from November 2009 to October 2011, where a prospective data base of all rickettsial infections is maintained. Confirmation of diagnosis was made when IgM and IgG immunofluorescent antibody titre of 1/32 and >1/256 respectively. Of the 210 clinical cases, 134 had cutoff antibody titers for Rickettsia conorii antigen for confirmation. All these 134 patients had fever and skin rash, and of them 132(98%) had discrete maculopapular rash while eight (6%) had fern leaf type skin necrosis. Eight patients (6%) had healed tick bite marks. Average size of a skin lesion was 5 mm and rash involved 52% of body surface, distributed mainly in limbs and back of the chest. Generally the facial and leg skin was slightly oedematous particularly in old aged patients. Sixteen patients (12%) had pain and swelling of ankle joints where swelling extended to feet and leg. Biopsies from skin rash of six patients showed evidence of cutaneous vasculitis and of them, 247 bp region of the 17-kDa spotted fever group specific protein antigen was amplified using PCR.

CONCLUSIONS

A discrete maculopapular rash and occasional variations such as fern leaf shape necrosis and arthritis are found in spotted fever group. Histology found vasculitis as the pathology of these lesions.

Spectrum of purpura fulminans

Purpura Fulminans is a severe disorder of acute onset with high morbidity and mortality. It is characterized by DIC with thrombocytopenia, hyofibrinogenemia, hypothrombinemia and anemia. It most often occurs in young with sudden appearance of symmetrical, tender, ecchymotic skin lesions usually involving the lower extremities. An infectious and noninfectious etiology has been proposed. Early recognition and early therapy with appropriate antibiotics and heparin is known to limit both morbidity and mortality. This article reports 5 cases of Purpura Fulminans treated at our centre with review of etiology, pathogenesis, clinical features and treatment.

Dermatoses from ticks

Ticks are ectoparasites that cause dermatologic disease directly by their bite and indirectly as vectors of bacterial, rickettsial, protozoal, and viral diseases. In North America, where ticks are the leading cause of vector-borne infection, dermatologists should recognize several tick species. Basic tick biology and identification will be reviewed. Tick bites cause a variety of acute and chronic skin lesions. The tick-borne diseases include Lyme disease, tick-borne relapsing fever, tularemia, babesiosis, Rocky Mountain spotted fever, other spotted fevers, ehrlichiosis, Colorado tick fever, and others. The epidemiology, clinical features, diagnosis, and treatment of these diseases are reviewed with an emphasis on cutaneous manifestations. Finally, the prevention of diseases caused by ticks is reviewed.

Purpura in infants and children

Hemorrhage into the skin (purpura) may result from abnormalities in any of the three components of hemostasis: platelets, plasma coagulation factors, and blood vessels. The morphology, size, and distribution of the hemorrhagic lesions are helpful diagnostic features. The main causes of purpura in the newborn and the more common hemorrhagic disorders in children are reviewed.

Dermatologic aspects of tick bites and tick-transmitted diseases

Dermatologic manifestations of tick bites and tickborne disease are not commonly encountered. However, recognition of the signs and histopathologic conditions of tick bites can be important to the diagnosis and management of small animal diseases. Understanding the local nodular inflammatory reaction to a tick bite can allay the owner's fear that a newly recognized nodule may be a malignant growth. Additionally, recognition of tick bites and pathognomonic dermatologic changes may provide important evidence in making a diagnosis of tick-transmitted diseases.

Purpura fulminans

Purpura fulminans presents as a catastrophic illness with gangrene of the distal extremities and necrosis of skin. The clinical picture consists of septicemia, shock, and disseminated intravascular coagulation. The Shwartzman and Arthus reactions are thought to be responsible for the pathogenesis of purpura fulminans. The exact mechanisms of these reactions are not completely understood. Immediate resuscitation is the treatment for shock and sepsis. Heparin is recommended to reverse the disseminated intravascular coagulation component of this disease. Surviving patients require treatment of skin necrosis and digital and extremity gangrene. The former are managed in a fashion similar to the management of burns. Amputation should be delayed until maximal collateral circulation has developed. A series of 10 patients is presented and 58 cases from the literature are analyzed.

The occurrence of eschars in Rocky Mountain spotted fever

Two patients with fatal, laboratory-confirmed Rocky Mountain spotted fever (RMSF) were noted early in their course to have a skin lesion characteristic of a rickettsial eschar. Postmortem immunofluorescent and histopathologic studies demonstrated that the lesions were sites of extensive contiguous infection by Rickettsia rickettsii with associated injury to numerous local blood vessels. Rickettsial vasculitis and occlusive luminal thrombosis were associated with dermal and epidermal coagulative necrosis forming the eschars. Both eschars were noted to be the sites of a bite. In one case the arthropod was identified as a tick. The clinical importance of the search for an eschar in a patient suspected of having RMSF is that diagnostic skin biopsy immunofluorescent demonstration of R. rickettsii may be performed prior to the onset of the rash.