On physical exam you note a well-appearing female who appears her stated age in no acute distress. Her vital signs are normal; she is afebrile. Her hips and knees have full flexion and extension with no obvious abnormality. Examination of the left lower extremity is significant for multiple fluid filled bullae on the distal third of the leg. There is marked tenderness to palpation all around the bullae as well as pain with any motion of the left ankle. The leg is obviously edematous when compared to the opposite limb. She has intact distal DP and PT pulses and capillary refill is slightly less than 2 seconds. She has intact sensation from the knee to the toes in all 5 distal nerve distributions. The patient’s gait is not tested due to her refusal to walk on the extremity.
Discussion:
The approach to the patient with fall and injury to the leg may seem mundane. However, the presence of blisters on the skin complicates this patient’s work up. Is the etiology something infectious? Autoimmune? Traumatic? As EPs, our role is to rule out the most immediate life and limb threatening diagnoses first.
Infection superimposed on traumatized skin is a potential cause of this patient’s blisters, and the astute physician should consider Staphylococcal scalded skin syndrome (SSSS), necrotizing fasciitis, gas gangrene and superficial cellulitis in this patient’s differential. Given that the patient is afebrile, non-toxic appearing and with no known risk factors for immune compromise, these major life or limb threatening infections are less likely. Furthermore, the lack of exfoliation of the skin and focal nature of the bullae pushes SSSS lower on our differential. Gas gangrene and necrotizing fasciitis, both diseases with high mortality, typically present with necrosis of underlying tissues leading to severe pain and muscle swelling; further signs and symptoms include pain out of proportion to the extent of overlying skin changes and tense edema with or without crepitus. Fortunately, our patient does not have any of these findings. Cellulitis commonly occurs in people with trauma or any break in the skin, but may even occur in patients with no discernible injury to the epidermis. Cellulitis with bullae may suggest an infection with Streptococcus pneumoniae, and less frequently, community acquired Staphylococci species including MRSA.
Other causes of blisters may be a result of an inflammatory response to trauma. Epidermolysis Bullosa, an inherited bullous disorder characterized by blister formation in response to mechanical trauma, falls into this category. Patients will report a history of frequent blistering as a result of often trivial mechanical trauma to the skin or mucosal surfaces. These are often painful and pruritic; mucosal involvement may include not only oral lesions, but pulmonary and gastrointestinal erosions as well. These sores are all prone to infection, which is a leading cause of morbidity and mortality in these patients. However, our patient has no such history and is a little old to be finding out about such a genetically transmitted entity at this time.
Keeping in mind that our patient fell through carpeting and the floor, one might consider friction blisters and contact dermatitis in the differential. Friction blisters arise as a result of friction between the skin and a rough surface. The hallmark of this entity is local irritation, but our patient does not demonstrate these findings. Contact dermatitis may also occur if the patient came into contact with a carpet cleansing compound which caused a local allergic reaction but this would be long-shot. It should also be remembered that our patient’s leg went through the floor; retained foreign body fragments, such as splinters of wood, may cause a local inflammatory response resulting in bullae formation. However, none of these processes seem likely with our patient’s history and physical examination. Bug bites such as from mosquitoes or flies as well as hymenoptera envenomation may also cause blistering on the skin and can be considered in our patient, although none of these entities will really explain the pain with ambulation seen in our patient.
One should always consider the patient’s social context when assessing such injuries. Are these wounds truly consistent with the mechanism described, or are they unlikely given the presented history? This is particularly important with pediatric and elderly patients, who may be the victims of non-accidental trauma. The patient’s bullae could be the result of thermal injuries, as partial thickness burns often create fluid filled blisters. Quite frequently, the victim of abuse is not forthcoming with information regarding the incident so it is critical to approach the issue with great care and sensitivity.
With this broad differential in mind, the patient should receive a focused work up in the ED. Radiography of the knee, tibia/fibula, ankle and foot are all indicated. Blood work including complete blood count (CBC), blood culture, metabolic panel, erythrocyte sedimentation rate (ESR) and coagulation profile should also be sought.
Our X-ray results come back first and reveal a distal tibia and fibula fracture with moderate displacement of the distal segment and no dislocation or fracture proximally at the knee (see next page). Free air is not seen tracking beneath the skin ruling out a gas-forming infection such as gangrene or necrotizing fascitis. Results of the blood work soon follow the radiographs but they are unremarkable, including a normal white blood cell count, hemoglobin level, hematocrit and ESR. In consultation with our orthopedic colleagues, the differential is now broadened to include fracture blisters as a possible diagnosis.
Fracture blisters are skin bullae or blisters that develop as a result of a shear injury mechanism with disruption of the junction between the dermis and the epidermis. These are potentially serious complications from high energy or twisting injuries to areas with little overlying soft tissue. Some authors feel that these blisters are an indicator of skin ischemia and while others believe them to be an early warning sign for compartment syndrome. They can also occur after excessive joint or fractured limb manipulation, dependent positioning, heat application or from peripheral vascular disease or lymphatic obstruction. The blisters may be solitary, multiple or massive. This often depends on the severity of the trauma and the region of injury. The most common locations for the development of this complication are the distal tibia, distal humerus (at the elbow) and the calcaneus.
Fracture blisters may contain clear, serous fluid or may be blood filled. In general, blood-containing blisters are associated with higher morbidity. Both types are associated with increased complications, as the presence of blisters delay surgical management and increase the risk of infection. Although there is a paucity of literature on the topic, most authors recommend leaving the blisters intact and, in the event of blister rupture, a topical antibiotic cream such as Silvadene or bacitracin should be applied in addition to local wound care with frequent dressing changes.
Perhaps even more effective, and more pertinent to the emergency physician, is prevention of blister development. Multiple case series have indicated that early reduction of a fracture to anatomical position and early surgical correction prevents the development of fracture blisters. It is believed that this occurs due to release of the fracture hematoma, reapproximation of disrupted soft tissues and fixation of bleeding fracture surfaces. One disadvantage of blister formation is that once blisters have developed, the surgical approach must be altered to avoid development of infection. The incidence of blister formation drops dramatically with surgical repair within 24 hours of injury.
Our patient is admitted to the orthopedic service and is started on IV antibiotics for the prevention of possible cellulitis, as well as receiving local wound care. After two days, her blood cultures do not grow any organisms and the patient is taken to the operating room for surgical repair of her fracture via a modified approach due to the presence of blisters on the lateral aspect of her extremity. The patient has an uneventful hospital course with normal serial compartment pressures. She has no signs of fascial involvement in the OR and good cosmetic wound reepithelialization over the blister sites.
