Ocular complications in patients with multiple myeloma are rare. These can be divided into two groups based on pathophysiology. The first group describes pathologies resulting from the infiltration or settling of plasma cells. The orbit is most involved in this group. Patients often present with double vision, visual impairment, and may clinically exhibit exophthalmos.(1)
The second group describes pathologies arising from the hematologic changes triggered by multiple myeloma. Common findings in this group include crystalline corneal deposits, ciliary body cysts, and retinal changes. (1) These changes caused by the deposition of light-chain proteins and can manifest as vortex keratopathy or as diffuse stromal haze. Furthermore, case reports of non-infectious anterior and intermediate uveitis are known. (2) On the retina, changes ranging from mild tortuosity of blood vessels with hemorrhages to central retinal vein occlusion due to hyper viscosity syndrome are more common. (2, 3)
An uncommon occurrence is the presence of subretinal fluid with detachment of the neurosensory retina. (3)In a case report from 2020, Wisely et al.(4) described a 78-year-old patient with exudative retinal detachment inferiorly in the right eye, along with multiple retinal hemorrhages and cystoid macular edema with subretinal fluid in both eyes. At that time, the diagnosis of multiple myeloma had not yet been established. (4)
Lam and Rodger(5) published a case report in 2014 about a 59-year-old woman with bilateral serous detachment of the central neurosensory retina in the macular region, venous stasis, and retinal hemorrhages. Grannis et al.(6) also described a case with bilateral central sub foveal serous detachment of the neurosensory retina, which regressed under chemotherapy (Bortezomib, Dexamethasone). (6)
Rusu et al. (7) reported a total of three patients with multiple myeloma and one patient with light-chain deposition disease. All patients exhibited central serous detachment of the neurosensory retina layer in the macular region. (7)
To the best of our knowledge, exudative detachment in the peripheral retinal area is described in only two cases. A patient with a complete bilateral exudative detachment of retinal layers is not known to us. Nevertheless, the same pathomechanism could have led to an exudative retinal detachment in our case as well.
Daicker et al.(8) demonstrated through electron microscopy of a Bruch's membrane that there were massive deposits of kappa light-chain proteins in a patient with multiple myeloma and Light-Chain Deposition Disease (LCDD) in an eye with exudative retinal detachment.
Pathophysiological, analogous to the basal membrane of the kidney, damage to the Bruch's membrane could occur due to the deposition of light-chain proteins. This could lead to a breakdown of the outer blood-retina barrier, allowing serous fluid to accumulate between the neurosensory retina and the retinal pigment epithelium. Our detection of light-chain proteins in the subretinal fluid supports this hypothesis.
Plerixafor is a CXCR4 chemokine receptor antagonist approved for cell mobilization before stem cell apheresis in multiple myeloma. It could be speculated, whether a similar mechanism occurs in the break down in interphotoreceptor matrix. Also, it could be assumed that the therapy with Plerixafor for cell mobilization led to a significant flushing out of light-chain proteins and thus to a definitive breakdown of the outer blood-retina barrier. However, there is no description in literature or corresponding product information. Nevertheless, we have reported a relevant adverse event. (9)
In summary, exudative retinal detachment in patients with multiple myeloma is a rare ocular complication. Whether this is related to Plerixafor remains unclear. We successfully identified light-chain proteins in subretinal fluid, allowing for a more precise understanding of the pathogenesis of the disease of multiple myeloma.