Teaching Case

A 23-year-old female patient with a one-year history of progressive left-shoulder pain and swelling. The patient also had abdominal pain and findings of obstructive uropathy at the time of presentation.

Figure 1: AP shoulder radiograph demonstrates an aggressive, lytic lesion involving the humeral head and proximal metaphysis.

Figure 2: Coronal T1 MR image demonstrates diffuse low-signal throughout the lesion in the proximal humerus, with soft-tissue extension medially. There are also enlarged, rounded axillary lymph nodes.

Figure 3: Coronal STIR MR image demonstrates heterogeneous signal hyperintensity of the humeral lesion and axillary lymph nodes.

Figure 4: Coronal TI fat sat MRI with IV-contrast shows diffuse enhancement of the bone lesion and lymph nodes.

Figure 5: Haematoxylin and eosin stained histopathologic specimen from CT-guided biopsy of the humeral lesion demonstrates a background of small lymphocytes, with scattered large cells that have abundant cytoplasm and large nuclei with prominent nucleoli, characteristic of Hodgkin cells (red circles). A binucleate cell (black circle) is suggestive of a Reed-Sternberg cell.

Hodgkin lymphoma (HL) constitutes 10-15% of all lymphomas [1], typically involving contiguous lymph nodes. At histopathology, HL is diagnosed by rare but characteristic Hodgkin and Reed-Sternberg cells [2], which are large cells with unusual morphology. Hodgkin cells are mononuclear, while Reed-Sternberg cells have paired nuclei that resemble owls’ eyes. Immunohistochemistry shows strong CD30 positivity, with CD15 positivity in most cases. Both stains were positive in this case, confirming the diagnosis.

Osseous lymphoma comprises 7% of bone malignancies [3], and is characterised as primary lymphoma of bone, with no other organ or lymph node involvement, and secondary lymphoma, with disease at other sites. The majority of primary and secondary bone lymphomas are non-Hodgkin lymphoma, specifically the diffuse large B cell type [4]. Secondary HL of bone is uncommon, with radiographic evidence of bone lesions reported in 10-15% of HL cases [5]. Bone lesions at initial HL presentation have only been reported rarely. Primary osseous HL is quite rare, comprising 6-8% of primary bone lymphomas [6].

The radiographic appearance of HL bone lesions may be lytic, sclerotic or mixed [5], often with aggressive features like cortical destruction and periosteal reaction. MRI will show an enhancing lesion with low TI and high T2 signal [3]. Osseous lymphoma will almost invariably show uptake on nuclear medicine bone scan and ¹⁸FDG PET [4]. PET is valuable to assess for other sites of disease, as primary HL is Stage 1 disease but secondary HL is Stage 4 in the Ann Arbor classification [7].

In addition to the humeral lesion, the patient had obstructive uropathy from abdominal lymphadenopathy, and the diagnosis of nodular sclerosing Hodgkin lymphoma was initially made by supraclavicular lymph node biopsy. However, majority of malignant bone tumours in a patient of this age are osteosarcoma or Ewing sarcoma [8]. Because of the concern for sarcoma, bone biopsy was also performed. The finding in this case that would be atypical for a sarcoma is lymph node enlargement, which might prompt the inclusion of lymphoma in the differential, even in a patient without known lymphoma.

Chemotherapy is the mainstay of treatment for osseous lymphoma, with radiation therapy being controversial [4]. Excisional surgery is contraindicated, although internal fixation may be needed in the setting of a pathological fracture. The lesion in this patient improved substantially after one round of chemotherapy, and did not require internal stabilisation.

Written informed patient consent for publication has been obtained.