91 year old female attended the emergency department after being found by carers unresponsive. She had been found on her right side with tenderness to her shoulder. She had recently been treated for a urinary tract infection and had a background of anaemia, weight loss and dementia
Plain radiographic findings
There is a large lytic lesion within the greater tuberosity of the right proximal humerus without any marginal sclerosis and intact bony trabeculae seen through the lucency. The features given the patient’s age are suspicious for a metastatic deposit.
MRI findings
Normal marrow signal at this site is evident. Thus the finding is in keeping with a pseudo lesion secondary to bone rarefaction.
Rarefaction in the humeral head is a well-known normal variant [1]. However, in this case the rarefaction was of such extent that it mimics a lytic lesion. Findings such as these are typically picked up incidentally; the difficulty, however, is determining the nature of such lesions. Imaging plays a crucial role in the diagnosis and management.
Due to normal marrow signal in the epiphysis being found on MR, the appearances can be attributed to bone rarefaction. This is the process of becoming less dense as seen in osteoporosis. Up to 98% of patients have a localised area of rarefaction in the humeral head adjacent to the greater tuberosity. This rarefaction can vary from minimal to cystic [2].
This entity should be classified as a ‘don’t touch lesion’ with no need to perform biopsy. These cases can be differentiated from aggressive lesions by criteria such as cortical destruction, periosteal reaction and a wider zone of transition [3]. Where there is a question regarding a true lesion or pseudocyst, as in our case, MRI is most useful as it will show whether the area consists of normal marrow.
CT is not particularly useful as appearances will be similar to that of plain radiographs.
Bone scintigraphy may show increased uptake due to hyperaemia and thus may convince a surgeon to perform a biopsy[4].
MR will demonstrate a similar look to osteoporosis with a heterogeneous appearance with rounded fatty lesions replacing normal marrow with coalescence often occurring. T1 is hyperintense and variable signal on T2. [5]
The metaphysis and proximal diaphysis demonstrate a hypointensity consistent with red marrow. In our case it is particularly prominent and is likely reactionary to the patient’s long-standing anaemia. On T1, the signal of red marrow is always higher in intensity compared to surrounding muscle. If this was to represent an infiltrative process, as in infection or neoplasm, only very rarely is this higher in signal intensity. Even cases of severe anaemia with marked haematopoietic activated (red) marrow will conform to this principle unless there is iron overload, such as haemochromatosis. [6]
There is no long term implication for the patient.
Take-Home Message / Teaching Points:
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Pseudocyst of the humeral head
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The patient is a 91-year-old female with a history of anemia, weight loss, and dementia. She presented this time due to right shoulder pain and a transient loss of consciousness.
Considering the patient’s advanced age, osteoporotic background, and the normal bone marrow signal on MRI, the first possibility is most likely.
Based on the imaging findings, the patient’s advanced age and osteoporotic background, and the MRI showing normal bone marrow signal, the most likely diagnosis is: Focal Osteoporosis (“Pseudocyst”) of the Humeral Head, rather than a true lytic or other aggressive lesion.
Such lesions generally do not require biopsy. If there are clinical doubts, close imaging follow-up can be considered. However, in most cases, they are considered a “don’t touch lesion,” avoiding unnecessary interventions.
Given the patient’s advanced age, as well as comorbidities such as anemia and reduced physical stamina, an individualized, gradual rehabilitation and exercise plan should be developed:
This report is a reference analysis based on available imaging and clinical information and does not replace professional in-person diagnosis or treatment advice. Specific treatment plans should be determined by a professional medical team according to the patient’s actual condition.
Pseudocyst of the humeral head
