[Clinicopathologic study of 10 cases of osteomalacia or rickets-associated mesenchymal tumors].
OBJECTIVE
To study the clinicopathologic features of osteomalacia or rickets-associated mesenchymal tumors.


METHODS
The clinical and pathologic findings of 10 cases of osteomalacia or rickets-associated mesenchymal tumors were evaluated. Hematoxylin and eosin stain, immunohistochemistry and histochemistry were performed on the archival paraffin sections.


RESULTS
Amongst the 10 patients studied, 6 were males and 4 were females. Their age at the time of operation ranged from 28 to 69 years ( mean = 45.6 years). A history of long-standing bone pain, arthralgia, limitation in movement, hypophosphatemia and hyperphosphaturia was present in all cases. The duration of symptoms ranged from 2 to 27 years (mean = 9.6 years). The tumor size ranged from 1 to 7 cm (mean size = 3.52 cm). Microscopically, the tumors were composed of various mesenchymal cells, including spindled fibroblast-like cells, adipocytes, chondroid cells and mucinous cells. The background was rich in blood vessels. In 8 of the 10 cases, there was also dystrophic calcification in an unusual flocculent or "grungy" pattern. Peripheral woven bone shell formation was noted in 2 cases and non-urate crystal deposition in 2 cases. Mitotic figures were rare in 9 cases. In 1 of the 10 cases however, mitotic figures and bizarre cells were commonly encountered. On immunohistochemical study, the tumor cells were all positive for vimentin. There was focal positivity for smooth muscle actin and CD34 in 5 and 3 cases respectively. The staining for desmin, S-100 and AE1/AE3 was negative. Ki-67 proliferation index was less than 4% in 8 cases and 30% in 1 case. Alcian blue-positive mucinous matrix and mucinous degeneration around vessels were noted in 8 cases.


CONCLUSIONS
Most of the osteomalacia or rickets-associated tumors are either benign or low-grade malignant mesenchymal tumors. They can be mistaken as other neoplasms due to the morphologic heterogeneity present. Thorough understanding of the associated clinical features and laboratory investigation results is helpful in arriving at the correct diagnosis.
Zhong
Ding-Rong
DR
Department of Pathology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China.
Liu
Tong-Hua
TH
Yang
Di
D
Feng
Rui-E
RE
Cui
Quan-Cai
QC
Luo
Yu-Feng
YF
Jia
Yong
Y
D000199:Actins / Q000378:metabolism; D000328:Adult; D000368:Aged; D018952:Antigens, CD34 / Q000378:metabolism; D001859:Bone Neoplasms / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D005260:Female; D005266:Femoral Neoplasms / Q000150:complications / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008297:Male; D008637:Mesenchymoma / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D008875:Middle Aged; D010018:Osteomalacia / Q000150:complications*; D012279:Rickets / Q000150:complications*; D012983:Soft Tissue Neoplasms / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D014746:Vimentin / Q000378:metabolism
D000199:Actins; D018952:Antigens, CD34; D014746:Vimentin; C498862:Acta2 protein, rat