Multiple myeloma with crystal-storing histiocytosis, crystalline podocytopathy, and light chain proximal tubulopathy, revealed by retinal abnormalities: A case report

Abstract

Rationale: Crystal sorting histiocytosis (CSH) is a rare disorder that is morphologically characterized by the accumulation of monoclonal immunoglobulin crystals, predominantly of a kappa light chain type, within lysosomes of macrophages. CSH may result in a variety of clinical manifestations depending on the involved organs. In this case report, we aim to describe a patient with ophthalmic manifestations which lead to the diagnosis of multiple myeloma with crystal-storing histiocytosis, crystalline podocytopathy, and light chain proximal tubulopathy.

Patient concerns: A 60-year-old male patient presented with progressive bilateral decreased vision for 2 years.

Diagnosis: Ophthalmic explorations showed bilateral macular and papillary edema, and multiple crystalline deposits in the anterior stromal cornea and in the retina. Laboratory tests showed nephrotic syndrome and renal dysfunction. Further work-up revealed IgG kappa multiple myeloma, with biopsy-proven combined crystalline podocytopathy and tubulopathy.

Interventions: The patient received chemotherapy (bortezomib, cyclophosphamide, and dexamethasone for 3 cycles, then bortezomib, lenalidomide, and dexamethasone).

Outcomes: Despite partial hematologic response and improvement of the papilledema and macular edema, the patient developed dialysis-dependent end-stage renal failure.

Lessons: This report, highlighting the protean presentation of paraprotein-mediated injuries, provides additional information on the ocular anomalies not previously described that may be associated with crystal-storing histiocytosis.

Figure 1

(A) RE and LE (slit lamp examination): diffuse intracorneal crystalline deposits; (B) RE and LE (in vivo confocal microscopy): granular and squarish hyperintense deposits in the anterior stromal cornea. LE = left eye, RE = right eye.

Figure 2

Multicolor (A) and infrared (B) imaging of fundus examination: visualization of the crystalline deposits as tiny bright spots on the papilla and macula of both eyes.

Figure 3

Fluorescein and ICG angiographies: macular and papillary leakage predominantly in the RE, with a discrete vasculitis, but no choroidal granuloma on ICG. RE = right eye.

Figure 4

(A) OCT B scan, before treatment: macular and papillary edema in both eyes, hyper-reflective spots particularly dense at the level of the inner plexiform/ganglion cell layers (yellow arrows); (B) OCT B scan, after treatment: reduction of papilledema and macular edema. OCT = optical coherence tomography.

Figure 5

(A) Numerous proximal tubular epithelial cells contained variably shaped intracytoplasmic fuchsinophilic crystals (Masson trichrome, original magnification ×1000). (B) Fuchsinophilic crystals were also noted in the cytoplasm of some podocytes and tubular epithelial cells shedded into tubular lumen (upper right corner) (Masson's trichrome, original magnification ×1000).

Figure 6

Proximal convoluted tubule with cystic dilatation of the lumen leading to breakage of the tubule. Interstitial histiocytes with crystalline inclusions (arrow). (Toluidine blue-stained 1-μm thick sections, original magninification ×1000).

Figure 7

Proximal tubular intra cytoplasmic crystals positive for anti-kappa conjugate (A) and negative for anti-lambda (B) (original magnification ×60 000, immunogold staining).