Rare Case of Orbital Involvement from Multiple Myeloma

An orbital mass is often the “tip of the iceberg”—it may be secondary to systemic malignancy, warn clinicians from University Sains Malaysia-Health Campus and Hospital Sultanah Bahiyah, both in Malaysia. Orbital metastases usually originate from lung and breast cancers, but these authors report on an unusual case of a patient whose orbital involvement stemmed from multiple myeloma (MM).

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The 85-year-old woman presented with right-eye proptosis, reduced visual acuity and diplopia. She had been bedridden with chronic back pain but had no symptoms of thyroid disorder or malignancy. Cardiovascular, breast, abdominal, and neurologic examinations were normal. She had no palpable lymph nodes. Blood investigations for infective and inflammatory causes were unremarkable.

However, a chest radiograph showed osteopenic bones, a pathologic fracture of the right clavicle, and an opacity obscuring the left retrocardiac region, suggesting a mass in the lower lobe of the left lung. The patient declined further imaging but underwent biopsy for the right orbital mass. Histopathologic examination revealed cells suggestive of MM. She was diagnosed with osseous plasmacytoma.

Orbital involvement in MM may be the first manifestation of systemic disease, the clinicians say. The diagnosis is usually based on clinical suspicion. Patients tend to present with nonspecific symptoms like back pain and fatigue. Computed tomography scanning is the imaging modality of choice, the authors say, but in older patients the findings may be hard to interpret. Thinning of the bone, for instance, may mimic metastases. Biopsy provides a definitive diagnosis and guides further management.

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Orbital involvement in MM is rare but treatable. Discovery of a plasmacytoma should always prompt investigation for systemic involvement, the authors advise, because the treatment and prognosis differ between the two. In their patient, proptosis secondary to the orbital plasmacytoma led them to discover end-organ damage in the form of multiple bone lesions. Solitary plasmacytoma would be treated with radiotherapy and resection; active MM with end-organ damage requires systemic chemotherapy.

Getting to the root of the problem can be difficult when the presentation is “insidious” and clinical features are nonspecific, the authors say. Patient and thorough investigation can make the difference in resolving the diagnostic imaging challenges.

Source:

Tai E, Sim SK, Haron J, Wan Hitam WH. BMJ Case Rep. 2017;2017: pii: bcr-2017-220895.
doi: 10.1136/bcr-2017-220895.