The present study revealed that the fibroblast-like type B synoviocytes (covering the surface of the synovial membrane in the rat temporomandibular joint) had muscle-specific caveolin-3 protein in their caveolae. The existence of two kinds of type B synoviocytes (with and without caveolin-3-immunoreactions even in the synovial lining layer) might reflect the functional difference between them. Anat Rec, 290:238-242, 2007. 2007 Wiley-Liss, Inc.

Caveolins-caveolin-1, -2, -3 (Cav1, 2, 3)-are major components of caveolae, which have diverse functions. Our recent study on the temporomandibular joint (TMJ) revealed expressions of Cav1 and muscle-specific Cav3 in some synovial fibroblast-like type B cells with well-developed caveolae. However, the involvement of Cav3 expression in the differentiation and maturation of type B cells remains unclear. The present study therefore examined the chronological alterations in the localization of Cav3 in the synovial lining cells of the rat TMJ during postnatal development by immunocytochemical techniques. Observations showed immature type B cells possessed a few caveolae with Cav1 but lacked Cav3 protein at postnatal day 5 (P5). At P14, Cav3-immunopositive type B cells first appeared in the synovial lining layer. They increased in number and immunointensity from P14 to P21 as occlusion became active. In immunoelectron microscopy and double immunolabeling with heat shock protein 25 (Hsp25) and Cav3, coexpressed type B cells developed rough endoplasmic reticulum and numerous caveolae, while the Cav3-immunonegative type B cell with Hsp25 immunoreaction possessed few of these. Results suggest that Cav3 expression, which is closely related to added functional stimuli, reflects the differentiation of the type B synoviocytes. Anat Rec,

The diagnosis of orofacial pain associated with temporomandibular disorders after repeated temporomandibular joint (TMJ) surgeries can be quite difficult. This case report describes a 52-year-old woman who had previously undergone five TMJ surgeries and developed divergent pain caused by a trigger point in the left preauricular area. Computed tomography and magnetic resonance imaging could not be used to identify a lesion because of metallic artifacts from a TMJ prosthesis. However, sonography indicated the location of the suspected lesion. Moreover, a neurological examination performed with local anesthesia was clinically effective in ruling out other diagnoses of orofacial pain. Ultimately, a histopathological examination of a biopsy specimen from the painful site confirmed the lesion to be a traumatic neuroma. This case report suggests the value of including traumatic neuroma in the differential diagnosis of patients with a history of previous TMJ surgery who present with orofacial pain in the region of the TMJ.