Renal Osteodystrophy in a Case of Suspected Plasma Cell Neoplasm

1.

A 70‐year‐old female with hypertension, type 2 diabetes mellitus, and end‐stage renal disease (ESRD) on dialysis was evaluated for left‐sided flank pain. A computed tomography (CT) scan of the abdomen and pelvis demonstrated diffuse osseous sclerosis and multiple lytic osseous lesions throughout the spine and pelvis, concerning for plasma cell myeloma. Initial laboratory studies showed mild anemia (hemoglobin of 11.8 g/dL, normal 12.6–15.9 g/dL), elevated serum creatinine of 3.91 mg/dL (normal 0.57–1.11 mg/dL), and elevated blood urea nitrogen (BUN) of 28 mg/dL (normal 8–24 mg/dL), consistent with the patient's history of ESRD. In addition, there was a markedly elevated serum parathyroid hormone (PTH) of 2015 pg/mL (normal 18–59 pg/mL), an elevated alkaline phosphatase of 763 U/L (normal 38–126 U/L), serum calcium of 8.9 mg/dL (normal 8.4–10.5 mg/dL), and elevated phosphorus of 6.5 mg/dL (normal 2.2–4.5 mg/dL). Serum protein electrophoresis and immunofixation failed to identify a monoclonal protein. Serum free light chain analysis demonstrated elevated kappa light chains of 151.73 mg/L (normal 3.30–1940 mg/L) and lambda free light chains of 148.39 mg/L (normal 5.71–26.30 mg/L) with a preserved kappa/lambda ratio of 1.02 (normal 0.26–1.65). Taken together, the laboratory findings were more consistent with reduced renal clearance than with a plasma cell neoplasm.

Given the clinical concern for plasma cell myeloma, a bone marrow biopsy was performed. Bone marrow aspirate smears demonstrated trilineage hematopoiesis without increased plasma cells (< 1% of marrow cellularity) or cytologic atypia. Flow cytometric immunophenotyping demonstrated a polytypic plasma cell population. Cytogenetic studies were not performed.

The bone marrow core biopsy demonstrated age‐appropriate cellularity with striking abnormalities of bone remodeling, including prominent irregular trabeculae lined by numerous osteoblasts, increased osteoid deposition, and an increased number of multinucleated osteoclasts occupying enlarged resorption bays (Figure 1). Reticulin and trichrome stains demonstrated mild‐to‐moderate marrow fibrosis (Figure 2). There was no morphologic evidence of a hematologic or metastatic malignancy. These morphologic findings, together with normal serum calcium and markedly elevated serum PTH, alkaline phosphatase, and phosphate levels, supported the diagnosis of high‐turnover renal osteodystrophy secondary to chronic kidney disease with secondary hyperparathyroidism.

FIGURE 1.

Hematoxylin and eosin‐stained bone marrow core biopsy. (A) Low magnification view of remodeled trabecular bone with paratrabecular fibrosis. (B) Paratrabecular fibrosis (black arrow) with occasional multinucleated osteoclasts (black arrowheads). (C) High magnification showing active bone remodeling with a large, multinucleated osteoclast (black arrowhead) lying within an enlarged resorption bay along with mineralized bone matrix (black arrow). (D) High magnification view demonstrating a prominent osteoblastic rim with tightly packed, large, cuboidal to polygonal cells with abundant amphophilic cytoplasm, eccentric round nuclei, and open chromatin (black arrowheads). Some of the osteoblasts are epithelioid with prominent nucleoli (white arrowheads). Photographs were taken on an Olympus BX41 microscope with 4× (A), 10× (B), 40× (C), and 100× (D) objectives equipped with an Olympus DP27 camera.

FIGURE 2.

Reticulin (A) and trichrome (B) stains performed on the bone marrow core biopsy demonstrating moderate paratrabecular reticulin fibrosis (black arrowheads) and mild collagen fibrosis (white arrowhead), respectively. Photographs were taken on an Olympus BX41 microscope with a 10× (A, B) objective equipped with an Olympus DP27 camera.

Renal osteodystrophy refers to the spectrum of skeletal abnormalities that occur as part of chronic kidney disease–mineral and bone disorder (CKD‐MBD) [1]. CKD‐MBD is characterized by both osteoclastic bone resorption and osteoblastic activity, leading to accelerated bone turnover [2]. Although renal osteodystrophy typically causes diffuse skeletal changes, it can present as focal osteolytic lesions that resemble primary bone neoplasms or plasma cell myeloma on imaging [3]. Recognition of this diagnostic pitfall is important, particularly in patients with advanced chronic kidney disease in whom serum free light chain concentrations may also be elevated secondary to impaired renal clearance.

This case highlights the importance of integrating clinical history, imaging studies, laboratory studies, and bone marrow morphology when evaluating patients with ESRD for suspected plasma cell myeloma. The absence of a monoclonal gammopathy or clonal plasma cell population, together with the characteristic histologic findings of increased bone turnover, supported renal osteodystrophy as the most likely explanation for the patient's osseous lesions.

Funding

The author has nothing to report.

Ethics Statement

The University of Utah Institutional Review Board (IRB) does not require ethical approval of studies that do not meet the definition of human subject research.

Consent

The included material is considered exempt by the University of Utah IRB. Consent was formally waived.

Conflicts of Interest

The author declares no conflicts of interest.

Hanley T. M., “Renal Osteodystrophy in a Case of Suspected Plasma Cell Neoplasm.” eJHaem 7, no. 5 (2026): e70421. 10.1002/jha2.70421

Data Availability Statement

Data sharing is not applicable to this article as no new data were created or analyzed in this study.