The Foot That Broke Both Hips: A Case Report and Literature Review of Tumor-Induced Osteomalacia

Abstract

Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome characterized by hypophosphatemia and clinical symptoms of osteomalacia. Only discussed as case reports, there is still limited knowledge of this condition as a potentially curable cause of osteomalacia among clinicians and pathologists. In this article, we present a case of tumor-induced osteomalacia in a 59-year-old gentleman followed by an up-to-date review of the existing literature on TIO.

Figure 1

Radiographic image of both femurs with arrows pointing towards the fracture lines (the right femur on the left side and the left femur on the right side).

Figure 2

Plastic-embedded trichrome-stained pictures of the bone with 20x magnification. The trichrome staining shows wide seams of unmineralized osteoid (red) that covers virtually all trabecular surfaces, suggesting a severe mineralization defect.

Figure 3

Fluorescence microscopic pictures of the tetracycline-labeled bone with 20x magnification. A severe mineralization defect is confirmed by an unstained section of the bone under fluorescence microscopy looking for tetracycline labeling which reveals faint fluorescence with a blurred pattern and no evidence of the typical double labeling of the bone matrix.

Figure 4

Positron emission tomographic image of the lower extremities showcasing a fluorodeoxyglucose (FDG) avid spot on the plantar surface of the left foot (arrow).

Figure 5

Low-power microscopic image (2x) showing a well-delineated tumor consisting of variegated mesenchymal components rich in small vessels with focal myxoid stroma.

Figure 6

Low-power microscopic image (10x) showing a tumor consisting of prominent small vessels, myxoid stroma, and scattered osteoclast-type giant cells.

Figure 7

High-power microscopic image (40x) showing a tumor consisting of bland spindle cells sitting in slightly myxoid stroma with an osteoclast-type giant cell.