Immunohistochemistry of symptomatic hypertrophy of the posterior longitudinal ligament with special reference to ligamentous ossification.
METHODS
Immnunohistochemical staining of the thickened posterior longitudinal ligament of the cervical spine.


OBJECTIVE
To clarify the histological characteristics of hypertrophy of the posterior longitudinal ligament (HPLL) of the cervical spine and the relationship between HPLL and ossification of the posterior longitudinal ligament (OPLL).


METHODS
Aichi Medical University, Aichi, Japan.


METHODS
Eight specimens of HPLL and two of OPLL were obtained during anterior decompressive surgery on the cervical spine from patients with myelopathy. Hematoxylin and eosin staining, alcian blue staining and immunohistochemical staining with antibodies against bone morphogenetic protein (BMP), transforming growth factor (TGF)-beta, proliferating cell nuclear antigen (PCNA), alkaline phosphatase (ALP) and osteopontin (OPN) were carried out on the specimens.


RESULTS
HPLL showed hyalinoid degeneration, the proliferation of chondrocytes and fibroblast-like spindle cells, infiltration of vessels and small ossification. In four cases, chondroid tissue was prominent with chondrocytes, which were expressed by ALP and OPN. The cells in HPLL were weakly or moderately stained by BMP, TGF-beta and PCNA. Their expression was similar to that of OPLL. Immunohistochemical staining was negative for all cells in the control cases.


CONCLUSIONS
Histological and biochemical evidence supports the hypothesis that HPLL transforms into OPLL. The positive expression of BMP and TGF-beta in HPLL cells of myelopathic patients, and their similarity to OPLL, suggest that these cells have the potential to differentiate into osteogenic cells. Of note, neither BMP nor TGF-beta was demonstrated in the PLL of control subjects. Furthermore, the expression of chondrocytes by ALP and OPN in cartilage-prominent HPLL suggests that the cartilage can be replaced by new bone.
Song
J
J
Department of Neurological Surgery, Aichi Medical University, Nagakute, Aichi-gun, Aichi, Japan.
Mizuno
J
J
Hashizume
Y
Y
Nakagawa
H
H
D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis / Q000378:metabolism* / Q000473:pathology*; D002574:Cervical Vertebrae / Q000378:metabolism / Q000473:pathology; D003240:Connective Tissue Diseases / Q000378:metabolism* / Q000473:pathology*; D016207:Cytokines / Q000378:metabolism*; D005260:Female; D006801:Humans; D006984:Hypertrophy / Q000378:metabolism / Q000473:pathology; D017846:Longitudinal Ligaments / Q000378:metabolism* / Q000473:pathology*; D008297:Male; D008875:Middle Aged
D016207:Cytokines