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.
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.
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.
Multiple thigh abscess and chest wall plasmocytoma
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Based on the provided imaging (chest radiograph, chest-abdomen-pelvis CT, and thigh MRI), the main characteristics are as follows:
In summary, the imaging appearance of the chest wall lesion strongly suggests a malignant tumor; the appearance of the bilateral thigh lesions is consistent with cystic or abscess-like changes.
Based on the medical history (diagnosed multiple myeloma and treatment with corticosteroids) and the imaging findings, the possible or differential diagnoses include:
Considering the clinical presentation, laboratory tests (positive blood culture, pus aspirate positive for culture), imaging features, and prior medical history, the following conclusions can be drawn:
As the patient’s immune system is suppressed due to multiple myeloma and recent corticosteroid use, any atypical infection must be taken seriously. Early detection and treatment of multiple abscesses are critical to improving prognosis.
Since this patient has multiple abscesses in the thigh region, rehabilitation exercises should be considered only after local inflammation and pain symptoms have improved. Overall, the recommendation is to follow a flexible, personalized, and gradual approach (FITT-VP principle).
If significant pain or signs of local redness or swelling recur, prompt medical evaluation is advised, and intense weight-bearing or vigorous exercise should be paused.
Disclaimer: This report is a reference medical analysis based on the information provided and cannot replace an in-person consultation or professional physician’s individualized advice. For any questions or if symptoms worsen, please consult a specialist immediately.
Multiple thigh abscess and chest wall plasmocytoma
