Skeletal Fluorosis Due To Inhalation Abuse of a Difluoroethane-Containing Computer Cleaner

Abstract

Skeletal fluorosis (SF) is endemic in many countries and millions of people are affected worldwide, whereas in the United States SF is rare with occasional descriptions of unique cases. We report a 28-year-old American man who was healthy until 2 years earlier when he gradually experienced difficulty walking and an abnormal gait, left hip pain, loss of mobility in his right wrist and forearm, and progressive deformities including enlargement of the digits of both hands. Dual-energy X-ray absorptiometry (DXA) of his lumbar spine, femoral neck, total hip, and the one-third forearm revealed bone mineral density (BMD) Z-scores of +6.2, +4.8, +3.0, and -0.2, respectively. Serum, urine, and bone fluoride levels were all elevated and ultimately explained by chronic sniffing abuse of a computer cleaner containing 1,1-difluoroethane. Our findings reflect SF due to the unusual cause of inhalation abuse of difluoroethane. Because this practice seems widespread, particularly in the young, there may be many more such cases. © 2016 American Society for Bone and Mineral Research.

Keywords: FLUORIDE; HYPEROSTOSIS; OSTEOSCLEROSIS; PERIOSTITIS.

Figure 1. Patient's Right Hand

Bony masses due to periostitis deformans are present along the phalanges of all digits.

Figure 2. Radiographs of the patient's hands

(A) Postero-anterior radiograph at age 28 years, while continuing to “huff”, demonstrates marked proliferating periosteal new bone (periostitis deformans) at many tubular bones (greatest in the proximal and middle phalanges) with some loss of the underlying cortex in the larger excrescences. The proliferations are bony with undulating peripheral margins that have distinct surfaces. Proliferations are also seen coming off the carpal bones, as well as off the radius and ulna. (B) Nearly two years later, after cessation of “huffing”, the proliferations have decreased and have smoother outer margins.

Figure 3. Bone scintigram

Mild diffuse increased uptake is present at the shoulders, hips, knees, ankles, wrists, and feet.

Figure 4. Patient Radiographs and CT of the Pelvis and Femoral Neck

(A) Antero-posterior pelvis shows diffuse osteosclerosis with marked osteophyte formations about the hips (arrows) greater on the left. Small marginal proliferations project off all the bones, but are not well shown. (B) CT of the left hip shows marked marginal osteophytes and bridging capsular and neck ossifications and impingement deformities (arrows). (C) CT shows cystic osteopenic changes in the femoral neck (arrows).

Figure 5. Patient Radiographs and CT of Left Elbow

Antero-posterior (A) and lateral (B) radiographs of the left elbow show new bone on each side of the elbow joint (arrows). CT shows osteophytes (C arrow) and periosteal new bone formations (D arrow).

Figure 6. Histology of Femoral Tissue

A,B) Low and higher power images of von Kossa-stained cortex show robust cortical bone and highlight an abundance of vascular channels. C) Visualization of an H&E stained image of cortex under polarized light demonstrates lamellar bone. D) Fluorescence imaging of an unstained section shows mineralization associated with osteoid, consistent with high levels of bone formation. E,F) Goldner trichrome stained sections of a fragment from an articular surface show irregular and disrupted cartilage, with regenerative nests of chondrocytes, and an abnormal osteochondral interface. Scale bars A,E = 1 mm; B,C,F = 500 mu; D = 200 mu.