UTC diagnosis
relies on clinical history, laboratory, radiological, and histological findings
(4). Lesions typically form in the periarticular soft tissue of the large
joints; given the slow initial growth, they present few clinical manifestations.
However, as the tumors grow, they can cause pain and functional disability in
the affected limb. Rarely, the underlying skin shows inflammatory signs,
ulceration, and secretion of milky material containing calcium salts, which may
resemble purulent material simulating an infectious condition (5). In our case, the patient presented with inflammatory
signs and drainage of seropurulent fluid in the affected area of the left
shoulder. This required surgical cleaning in the operating room and initiation
of antibiotic therapy despite negative culture results.
Uncontrolled
hyperphosphatemia, with a CaxP product above 60-68 mg²/dL² has been described
as one of the findings reported in PD patients with UTC that facilitates
extraosseous calcification. (3,8) Other findings associated with
pathogenesis include secondary hyperparathyroidism (iPTH >400 pg/ml), aluminum
intoxication, excessive use of calcium chelators, or active vitamin D analogs,
so that a bone mineral profile study is necessary when UTC is suspected. (4,7,8)
In the
present case the CaxP product above 60 and severe hyperparathyroidism with a PTH>900
pg/ml, as the presence of calcinosis cutis, vascular calcification, and the
calcified tumor lesion in the shoulder observed in the CT scan, allowed the
suspicion of UTC, which is confirmed by the presence of multinucleated giant cells
type foreign material due to calcium deposition in the biopsy.
When UTC is
suspected, it´s necessary to rule out other pathologies such as infectious
diseases (cellulitis, arthritis, abscesses, or acute osteomyelitis), inflammatory
diseases (bursitis, reactive arthritis, or arthritis secondary to systemic
disease), metabolic diseases (gouty arthritis or chondrocalcinosis) and other
calcifying diseases (4, 6, 7, 8).
Medical
treatment for UTC includes dietary phosphorus restriction, the use of
non-calcium chelators, calcimimetics that do not produce calcium elevation such
as cinacalcet, and the use of peritoneal dialysis solutions with low calcium
content (1,4,7,9,10). Given the severity of the picture or the
persistence of the mass despite the medical treatment previously described,
surgical resection of the parathyroid glands and renal transplantation are
suggested. The latter has been shown to have higher rates of complete resolution
(11-14). Currently, our patient has
had the parathyroidectomy and is being evaluated for kidney transplant waiting
list.
This
case represents the first report of UTC in Perú in which the diagnosis has been
confirmed by biopsy of the tumor lesion, so we emphasize the importance of
ruling out this pathology in all patients with CKD on dialysis who present bone
mineral disease associated with tumor lesions in the clinical examination and
the presence of periarticular calcifications in radiography. With respect to
treatment, the use of non-calcium chelators, and calcimimetics that do not
produce elevation of calcium concentrate should be considered at the beginning.
In case medical therapy proves ineffective, the option of surgical treatment,
such as parathyroidectomy and renal transplantation, should be considered.