Masafumi Kuroda

Massive osteolysis of the mandible.

This report deals with a massive osteolysis, which is a rare disease characterized by the progressive dissolution of contiguous osseous structure, occurring in the mandible of a 46‐year‐old Japanese female. Histopathologic examination of the amputation material revealed that the mandibular body, ramus, condylar and coronoid processes were completely replaced by fibrous tissue, but inferior alveolar nerve and artery in the lesion were intact. A few small islands of osteoid tissue or immature fibrous bone were seen in the lesion. In the transitional area between the lesion and normal bone, active absorption of bone trabeculae was in progress and intertrabecular spaces were occupied by densely packed fibroblastic cells, however, angiomatous proliferation of vessels was not observed. A few bone trabeculae were surrounded by osteoclasts, but osteoclasts might not play a primary etiological role in massive osteolysis.

MELANOCYTES IN ODONTOGENIC KERATOCYST

Melanocytes in odontogenic keratocyst (OKC) were studied histopath‐ologically. As a result, melanocytes were observed within the basal layer of lining epithelium in five of 47 cases with OKC, with the overall prevalence being 10.6 per cent. Although no conclusion could be drawn from the present examination as to the origin of melanocytes in OKC, its possible histogenesis was discussed. ACTA PATHOL. JPN. 35: 899–903, 1985.

PIGMENTED VARIANT OF CALCIFYING ODONTOGENIC

A case of the pigmented variant of calcifying odontogenic cyst occurring in a 21‐year‐old Japanese male is reported, and a review of previously reported cases of the lesion is included. In addition to the characteristic histopathologic features of calcifying odontogenic cyst, dendritic cells containing melanin pigment were widely distributed in the epithelial layer and melanin pigment was also found in the epithelial cells including ghost cells in the present case. Although no conclusion could be drawn from the present examination as to the origin of melanin pigment in the calcifying odontogenic cyst, it is thought that the role of racial pigmentation is one of the important factors in occurrence of pigmented odontogenic lesions. ACTA PATHOL. JPN. 35 : 1023–1027, 1985.

Ameloblastoma with Prominent Stromal Ossification

A large ameloblastoma with prominent stromal ossification is reported. The patient was a 39 year old Japanese male with diffuse swelling of the mandible from the left molar to the right premolar region. Radiographic examination showed a radiopaque lesion suggestive of a fibro osseous lesion. However, histologic examination revealed the lesion to be a variant of follicular ameloblastoma. Most of the tumor cells appeared to be squamous metaplasia. The stroma was abundant, with prominent formation of bone trabeculae rimmed by osteoblasts. Differentiation of mesenchymal cells into active osteoblasts with formation of new bone trabeculae was frequently found in the stroma. The prominent stromal bone formation appeared to be reactive in nature, although it remains uncertain whether this type of ameloblastoma can be regarded as a discrete clinicopathologic entity. Acta Pathol Jpn 40: 780 784, 1990.

Ameloblastic Odontosarcoma (Ameloblastic Fibro‐odontosarcoma) in the Mandible

A case of ameloblastic odontosarcoma (ameloblastic fibro‐odontosarcoma) originating in the mandible is reported. The patient was a 23 year‐old Japanese male with diffuse swelling of the mandible from the left premolar to the ramus region. A biopsy specimen showed the histopath‐ological features of ameloblastic fibrosarcoma. Histologic examination of the surgical specimen revealed various amounts of dysplastic dentin and dentinal matrix which were closely associated with both mesenchymal and epithelial components throughout the lesion. In addition, a small amount of abortive enamel matrix, which was in close contact with ameloblastoid cells of epithelial nests, was found by extensive sampling of the resected specimen. Therefore the present case was diagnosed as ameloblastic odontosarcoma. After 2 years, the patient died of uncontrollable local recurrence and extension to the cranial base. Acta Pathol Jpn 40: 832 837, 1990.

AMELOBLASTOMA OF MUCOSAL ORIGIN

Histopathological, histochemical and ultrastructural findings of an extraosseous ameloblastoma occurring in an 89‐year‐old woman are reported. Rete pegs of the gingival epithelium covering the lesion showed marked extension into the lesion, and direct continuity between the extended rete pegs and tumor follicles was evident. Ultrastructural examination showed that the rete pegs gradually became transformed into double‐stranded epithelial cords as they elongated deeply, and that the ends of these epithelial cords gradually became transformed into tumor follicles. These findings suggest that the potential for differentiation is maintained in the basal cells of the gingival epithelium throughout life, and can be triggered by unknown stimuli. The ultrastructure of the tumor follicles was similar to that of intraosseous follicular ameloblastoma, but was different from that of cutaneous basal cell carcinoma. Histochemical staining for keratin protein revealed that the central cells of tumor follicles and the covering epithelium were positive, whereas the peripheral cells of tumor follicles and the elongated rete pegs were negative. ACTA PATHOL JPN38: 1053∼1060, 1988.

Failure of root development of human permanent teeth following irradiation

Complete absence of root formation of the upper incisors, canine and first premolar was reported in a 27-year-old female who had received radiation therapy for a retinal glioma of the right eye at age of 3 years 1 month. Ground and decalcified sections showed no remarkable changes in enamel and dentin of the crowns, but the pulp floor was closed by irregular dentin deposit despite the absence of root formation. The outer surface of the irregular dentin was covered by acellular cementum, and the periodontal membrane was undeveloped. A slight degree of fibrosis was seen in the pulp, but the coronal part of the dentin was lined by odontoblasts. The theory that tooth eruption is caused by the growth of the root is not substantiated by the observation in this case.

Synchronous benign epithelial tumors arising in the palatal minor salivary gland. First report of an unusual minor salivary gland lesion.

A review of the literature shows that unilateral benign salivary gland tumors of different histologic types in a single gland are so rare as to be curiosities, and all of such reported tumors have arisen in the parotid gland. The present paper reports a case of synchronous benign epithelial tumors of different histologic type arising in the palatal minor salivary gland of a 57 year old woman who had first noted palatal swelling about 20 years previously. Pathologically, the lesion was composed of two distinct tumors, pleomorphic adenoma and lumenless trabecular adenoma, which were sharply demarcated from each other by a thin layer of fibrous connective tissue. Foci of tumor cells with cellular atypia were seen in some areas of the pleomorphic adenoma. The present case is thought to represent a previously undescribed component within the spectrum of minor salivary gland tumors. Acta Pathol Jpn 40: 143–148, 1990.

MINOR SALIVARY GLAND SWELLING IN PATIENT WITH SJOGREN'S SYNDROME

A case of Sjögrens syndrome with an unusual minor salivary gland swelling is reported. The patient was a 63‐year‐old female with a chief complaint of palatal swelling and dry mouth. Clinical examination revealed diffuse swelling of the hard palate and bilateral parotid regions, and sialographic examination of the parotid gland showed evidence of sialoangiectasia. His‐topathological findings of the palatal and parotid lesions revealed intense lymphoid cell infiltration replacing the salivary gland parenchyma, and scattered epimyoepithelial islands throughout the lesions. Although it is well known that major salivary gland swelling caused by marked lymphoid cell infiltration is one of the common features in patients with Sjogrens syndrome, a similar swelling in the region of the minor salivary glands is not usually apparent.