Late‐onset extensive haematoma mimicking cellulitis

Abstract

Cellulitis is a microbial infection of the deep dermis and the subcutaneous tissue. Several non‐infectious disorders, such as contact dermatitis, insect bites, stasis dermatitis, and lipodermatosclerosis, masquerade as infectious cellulitis. There are no specific criteria for the diagnosis of cellulitis; thus, it is challenging to correctly diagnose true cellulitis. For previously assumed cellulitis cases that were refractory to conventional antimicrobial treatment, thoroughly investigating the circumstances of symptom initiation, recording the medical history, and performing an attentive physical examination of the patient is critical for distinguishing true cellulitis from conditions that mimic cellulitis. The inquiry should be personalised according to the patient's age and the prescribed medication. Furthermore, imaging studies, including ultrasonography and magnetic resonance imaging, should be considered on certain occasions to non‐invasively aid the differential diagnosis.

1. INTRODUCTION

Cellulitis is often misdiagnosed. More than 10% of the patients diagnosed with cellulitis do not actually have cellulitis.1 This is unfortunate as it leads to the excessive and incorrect use of antibiotics and delays appropriate therapy.2 Certain medical conditions of the connective tissue, such as contact dermatitis, insect stings, lupus erythematosus, sarcoidosis, lymphoma, and panniculitis, show symptoms and laboratory test results similar to those of cellulitis. Thus, the accompanying factors, including a previous history of cellulitis, obesity, underlying diseases, and prescribed medication, should be carefully investigated, together with a thorough physical examination, and the patient's age must also be considered. The differential diagnosis of cellulitis should include haematoma, especially for older patients who regularly take anticoagulants for long periods of time. Furthermore, the initial response of the lesion to the administered antibiotics for the first few days should be meticulously observed to ensure the proper diagnosis of cellulitis.

2. CASE PRESENTATION

A 74‐year‐old woman was referred to our dermatology department from a primary clinic for further evaluation and proper treatment of a worsening erythematous swollen patch that had developed on her right shin after a sliding trauma on the stairs 2 weeks before. The patient described that the lesion and symptoms were initially minimal with slight scratch marks on the skin, but the swelling and pain on her right lower leg insidiously worsened. Although the primary physician treated her lesion with antibiotics because of suspecting trauma‐induced cellulitis, the lesion showed increasing oedema and tenderness. The patient had a history of diabetes mellitus and hypertension and had been taking appropriately prescribed medicines, including cilostazol, an antiplatelet agent.

Generalised and moderate swelling with erythema was observed on her right lower leg with severe tenderness and no remarkable heat sensation. Diffuse whitish haziness, indicative of soft‐tissue swelling around the upper half of the right tibia and fibula, was visible on a simple radiograph (Figure 1). The initial biochemical laboratory results demonstrated elevated C‐reactive protein levels and erythrocyte sedimentation rates. Prothrombin time and activated partial thromboplastin time (APTT) were normal. Taking the radiographic imaging findings and lab results into consideration, we first suspected that her lesion was cellulitis which was enlarging with inflammation and showing some antibiotic resistance. We initiated the patient on broad‐spectrum antibiotics after performing a bacterial culture of the material from an attempted drainage. Possible pus drainage was attempted to promote healing and reduce the pain and swelling. However, only a small lump of blood aggregate was squeezed out of the drain hole (Figure 2). As a criterion to rule out other diseases that could mimic cellulitis, magnetic resonance imaging (MRI) was performed for further evaluation. The MRI demonstrated a 4.4 × 1.5 × 12.4 cm thick‐walled pseudo‐lobulated material in the anterior mid‐shin without involvement of the underlying muscles (Figure 3). We clinically suspected an extensive haematoma as the patient's leg showed no improvement despite ongoing intravenous antibiotic treatment and based on the findings of the bloody lump from the drain hole. Therefore, we transferred her to the orthopaedic department for a wider incision and drainage of a clinically speculated haematoma. This eventually led to the removal of a large haematoma, suggesting a late‐onset haematoma after the traumatic event rather than classic cellulitis. The erythema, tenderness, and swelling resolved promptly after the temporary cessation of cilostazol and the haematoma evacuation.

Figure 1.

A diffuse whitish haziness indicative of soft‐tissue swelling around the upper part of the right tibia and fibular is visible on a simple radiograph

Figure 2.

The aggregated blood clot squeezed out of the drain holes from the oedematous and erythematous right lower leg

Figure 3.

Lower‐extremity magnetic resonance imaging finding of 4.4 × 1.5 × 12.4 cm thick‐walled lobulation in the shin area without muscle involvement. A, Longitudinal plane. B, Transverse plane

3. DISCUSSION

Cellulitis is an infection of the deep dermis and the subcutaneous tissue that occurs when pathogens gain entry into the dermis through breaks in the skin. Patients with cellulitis present with expanding lesion erythema, warmth, tenderness, and swelling. Cultures performed from needle aspirations or biopsies typically yield negative results.3 A systematic review of 808 adult and paediatric cellulitis patients undergoing needle aspirations or punch biopsies found that only 16% had cultures that established a bacterial diagnosis.3, 4 As culture results are usually unrevealing and take time to acquire, most cellulitis cases are clinically diagnosed by history and physical examination. However, the diagnosis can often be erroneous, and physicians may be challenged by cases that do not respond to the initial antibiotic regimen. In a study evaluating the appropriate therapeutic duration for cellulitis, 23 of 169 cellulitis patients (13.6%) who were referred for participation in the trial were misdiagnosed.5 The most common disorders mistaken for lower‐limb cellulitis are venous eczema (stasis dermatitis), lipodermatosclerosis, irritant dermatitis (eczema), and lymphoedema.6 Less commonly, urticaria, lupus erythematosus panniculitis, and —rarely—haematomas can mimic cellulitis.

In a case report, a 38‐year‐old man with a prolonged APTT was mistakenly diagnosed with cellulitis when the actual diagnosis was haematoma formation because of a bleeding disorder.7 In our case, prolongation of prothrombin time and APTT were not seen. However, the patient was on cilostazol, an antiplatelet agent, and the lesion appeared following a history of trauma. Older patients with a long‐term history of antiplatelet agent or anticoagulant use have an increased bleeding tendency following trauma.8 Late‐onset haemorrhagic events in the brain or other internal organs are commonly observed in these patients. In the same context, late‐onset subcutaneous haematoma with a time delay after trauma can occur and simulate cellulitis. In such cases, radiological examination findings can provide clues and should be considered to aid in the correct diagnosis and facilitate possible surgical treatment.9

Furthermore, the initial response to administered antibiotics should be closely monitored to avoid misdiagnosis and losing essential time in the appropriate treatment of conditions that mimic cellulitis.

4. CONCLUSIONS

In conclusion, elderly patients with reduced resilience and weakened connective tissues who are taking antiplatelet or anticoagulant medications may present with haematoma formation mimicking cellulitis. Thus, haematoma should be considered one of the differential diagnoses for cellulitis in such cases, especially for those with a prior history of trauma.

Baek YS, Song JY, Jeong KM, Jeon J. Late‐onset extensive haematoma mimicking cellulitis. Int Wound J. 2019;16:297–299. 10.1111/iwj.13014