CASE 15793 Published on 13.07.2018

A case of multiple thigh abscesses in a patient with multiple myeloma

Section

Musculoskeletal system

Case Type

Clinical Cases

Authors

J Todd MRCS, M Rahiminejad MD, L DeSoysa FRCPath MRCP and S Muthu FRCR

Department of Radiology, Wrexham Maelor Hospital, North Wales, UK

Email:joanne_todd@hotmail.com
Patient

59 years, male

Categories
Area of Interest Musculoskeletal soft tissue, Thoracic wall ; Imaging Technique MR, CT
Clinical History

A 59-year-old male patient with recently diagnosed multiple myeloma, confirmed on bone trephine, presented unwell with a chest wall mass. CXR and a subsequent CT chest abdomen and pelvis were performed. The patient then developed bilateral thigh pain and was unable to mobilise, MRI thighs was then also performed.

Imaging Findings

Figure 1. The chest X-ray shows a large left upper zone mass with an incomplete border sign indicating an extrapulmonary lesion.

Figure 2-3 CT chest revealed a 5x6 cm mass of soft tissue density arising from the anterior aspect of the left second rib. There were also several left axillary, supraclavicular and mediastinal pathological lymph nodes. Appearances of the soft tissue mass are suspicious of plasmocytoma in the context of known multiple myeloma. This was confirmed by histology obtained from ultrasound-guided core biopsy.

Figure 4-6 MRI both thighs: Multiple peripherally enhancing well-defined cyst-like lesions in the intramuscular plane, with no solid components identified. The largest lesion was in the right adductor magnus muscle belly measuring 9 cms. Differential diagnoses include multiple abscesses or neoplastic cystic metastases.

Discussion

Patients with multiple myeloma can mount a poor immune response to infection and therefore can present atypically. This patient had recently received pulsed dexamethasone as part of his multiple myeloma treatment, this may partly explain the atypical presentation of the multiple thigh abcesses.
At the time of the MRI, the patient did not have pyrexia or any other clinical sign of sepsis, the only clinical complaint was from pain from the local effects of the multiple abscesses. The lesions were not palpable or visible on inspection of the patient's legs. A dedicated MRI of the thighs was performed based on symptoms of pain and inability to mobilise, screening of other areas was not performed.
The distribution of the abscesses was unusual, there was no history of local trauma, injection or recent acute illness.
The MRI appearances of the multiple lesions were suspicious for abscess or malignant deposits; hence the need for ultrasound-guided aspiration in order to obtain a histological/microbiological diagnosis. Gram positive cocci (Staphylococcus aureus) were grown in the peripheral blood culture and the frank pus that was aspirated from one of the thigh lesions. An ultrasound-guided core biopsy of the chest wall lesion confirmed a diagnosis of plasmocytoma.

It is well documented in the literature that infection is a significant cause of mortality and morbidity in patients with multiple myeloma. [1-3] It has been observed that up to 45% of early deaths (within 6 months of diagnosis) were due to infection) [4]. It is thought that the underlying plasma cell disorder causes inherent immunodeficiency which leads to susceptibility to infection.

In this patient's case the early diagnosis of abscess was crucial, as this is a treatable condition if detected early enough. The patient presented atypically due to concurrent underlying imunosuppression (due to presence of multiple myeloma and recent dexamethasone treatment), in such patients atypical presentation of infection should always be considered.

Differential Diagnosis List
Multiple thigh abscess and chest wall plasmocytoma
Multiple thigh abscesses
Malignant intramuscular deposits
Plasmocytoma
Multiple myeloma
Final Diagnosis
Multiple thigh abscess and chest wall plasmocytoma
Case information
URL: https://eurorad.org/case/15793
DOI: 10.1594/EURORAD/CASE.15793
ISSN: 1563-4086
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