735
LEUNG. WONG, AND Ll
J Oral Maxillofac 481735-738.
Surg
1990
Oral Leiomyoma: Case Report KAM-WING LEUNG, DDS,* DANIEL YONG-KIE WONG, DDS, MS,t AND WING-YIN LI, DDS$
Leiomyoma is a benign tumor of smooth muscle origin that most often occurs in the uterus and gastrointestinal tract. It is seldom found in the oral cavity because of the paucity of smooth muscle. The earliest report of an oral leiomyoma was by Blanc’ in 1884. Since that time many other reports have appeared in the literature.2‘26 A 1986 literature review by Svane et al’ reported 116 cases of oral leiomyoma, including 30 from the Japanese literature.3 We have found 9 additional oral leiomyomas ,4-7 including the one in this article, making a total of 125 reports of intraoral leiomyomas (Table 1). This article describes a primary leiomyoma found in the lower buccal sulcus of a 26-year-old Chinese woman.
* Chief Resident and Clinical Instructor, Oral and Maxillofacial Surgery. Dental Department, Veterans General Hospital; and School of Dentistry, National Yang Ming Medical College, Taipei, Taiwan. t Lecturer and Attending Physician, Oral and Maxillofacial Surgery, Dental Department, Veterans General Hospital; and School of Dentistry, National Yang Ming Medical College, Taipei, Taiwan. $ Lecturer and Attending Physician, Pathology Department. Veterans General Hospital; and School of Medicine, National Yang Ming Medical College, Taipei, Taiwan. Address correspondence and reprint requests to Dr Wong: Division of Oral and Maxillofacial Surgery, Dental Department, Veterans General Hospital, VACRS, Taipei, Taiwan 11217, Republic of China. C 1990 American geons
Association
of Oral and Maxillofacial
Sur-
0278-2391190/4807-0013$3.0010 Table 1. No.
Report of a Case A nodular mass was found in the mandibular left buccal vestibule between the first and second molar region. It measured approximately 1.0 X 0.5 X 0.5 cm, and had been noticed by the patient for about 2 weeks (Fig 1). The lesion was shiny and firm, and the overlying mucosa was intact and smooth. There was no cervical lymph node enlargement. Panoramic and periapical radiographs of the involved region were taken and revealed no evidence of bony destruction. An excisional biopsy was performed in the outpatient department under local anesthesia. The biopsy report stated that the lesion was a leiomyoma and that the tumor had been incompletely excised. The patient was admitted to the hospital for a further surgical procedure. A wide excision in the previous biopsy site was performed under general anesthesia. The operation consisted of total removal of the residual tumor with surrounding mucosa and approximately 5 mm of the underlying muscle. The wound was closed primarily. The subsequent histology report showed the resected margin to be free of tumor. The surgical wound healed without complication. No tumor recurrence was noted at the l-year follow-up examination. The specimen consisted of a piece of grey-white soft tissue with covering mucosa measuring approximately 1.6 x 1.0 x 0.5 cm. The microscopic sections were composed of tumor cells arranged in a whorling and fascicular arrangement. No mitotic figures were seen (Fig 2). Irregular margins of the tumor with foci of expansive growth were evident. The S-100 protein was negative (Fig 3), whereas both Van Gieson’s and Masson’s trichrome stains were positive for muscle fibers (Fig 4), and the presence of myofibrils was confirmed using Mallory’s phosphotungstic acid-hematoxylin (PTAH) staining (Fig 5). The final diagnosis was solid leiomyoma of the buccal sulcus without signs of malignancy.
Nine New Cases of Intraoral Leiomyoma From 1996 to 1987 Author
Year
AgelSex
Site
Esguep and Sol& Esguep and Sola? Esguep and Sola Esguep and Sola? Esguep and Sola McMillian et al* Greenberg et aI6 Kawakami et al’ Leung et al
1986 1986 1986 1986 1986 1986 1987 1987 1987
48/F 47/M 50/M 42fM 24/F 54iM 73lM 33tM 26/F
Hard palate Lower lip Upper lip Soft palate Hard palate Central mandible Tonsil Lower lip Lower buccal sulcus
ORAL LEIOMYOMA:
FIGURE 1. Preoperative photograph showing tumor located in the buccal sulcus of first and second molar of left side of the mandible.
CASE REPORT
FIGURE 4. Masson’s trichrome-stained section shows the muscle cells stained red and collagen fiber stained blue. It is suggested that the tumor is of myogenous origin. (Original magnification, X400.)
Discussion
FIGURE 2. Photomicrograph of leiomyoma which is composed of spindle-shaped cells with blunt-ended nuclei arranged in whorling and fascicular arrangement. No mitotic fgmre is identified. (Hematoxylin-eosin stain. Original magnification, x 100.)
FIGURE 3. S-100 protein stain showed negative finding, suggesting that the tumor was not of neurogenic origin. (Original magnitication, X 100.)
Leiomyoma is rarely found in the oral cavity because of the relatively small amount of smooth muscle. In the experience of Farman and Kay,* based on 7,748 leiomyomas, approximately 95% occurred within the female genital tract, and only 5 (0.064%) were found in the oral cavity. Various authors have postulated different theories regarding the origin of leiomyoma in the oral cavity.9-‘3 Stout’ suggested that their origin was the smooth muscle of the tunica media of the blood vessel wall. Other sources were thought to be circumvallate papillae of the tongue, the submandibular duct, heterotopic embryonic muscle tissue, and the aberrant arrectors pilorum muscles in the cheek.‘0-13 According to the World Health Organization
FIGURE 5. Mallory’s PTAH-stained section shows the striated muscle stained red and smooth muscle cells stained orange. It is highly suggestive of smooth muscle origin. (Original magnification, x 100.)
737
LEUNG, WONG, AND LI
classification,‘4 there are three types of leiomyomas: leiomyomas (solid), angiomyoma (vascular leiomyoma), and epitheloid leiomyoma (leiomyoblastoma). Microscopically, the solid leiomyoma is a well-circumscribed tumor that is not associated with a blood vessel and which consists of intertwining spindle cells with varying amounts of collagen. The collagen may become so prominent as to obscure the true nature of the lesion. The muscle nuclei are elongated, blunted, and do not readily stain. The bundles of fibers usually form whorls because they are cut in different planes. Intracytoplasmic myofibrils can be demonstrated with special stains. Mitoses are usually rare. Vascular leiomyomas are associated with blood vessels from which they may derive their origin from the smooth muscle of the tunica media. They have a thick wall with a small rounded or stellate lumen, which often contains red blood cells. The smooth muscle fibers of the vessels are circularly disposed about the lumen and are associated with collagen fibers. Many of the vessels do not have muscular walls, only an endothelial lining. The leiomyoblastoma is composed of rounded or polygonal cells with a clear zone around the nucleus and an acidophilic cytoplasm. Smooth muscle fibers are rarely found. l4 From an extensive review of the literature, it was found that 74% of oral leiomyomas previously reported were angioleiomyomas, and 25% were solid leiomyomas. Only one case of leiomyoblastoma has been reported2 (Table 2). This is probably due to the fact that the main source of smooth muscle in the mouth is the blood vessel wall. The most common sites of oral leiomyomas are the lips (24.4%), followed by the palate (21.1%), tongue (19.5%), and cheek (16.3%) (Table 3). The sex ratio of reported cases is approximately about I: 1, with 63 males and 55 females. The patients’ ages ranged from infancy to 85 years with a mean age of 46 years. The greatest incidence occurred between 40 and 59 years of age (Table 4). Clinically, oral leiomyomas usually grow slowly, are painless superficial lesions, and often have a firm but elastic consistency. The tumor does not ulcerate and resembles normal mucosa in both color and texture. The size varies from a few millimeters to 3 cm. The majority of cases reported were asymptomatic. However, three lesions of the tongue reported by Blanc,’ Bertelli,” and Praal16 were painful. Other peculiar symptoms include a change in the patient’s voice, sore throat, difficulty in swallowing, and limitation of mouth opening. L,9,‘7*18 Recurrences are rarely seen after a normal follow-up period of 6 years. There were only three recurrences reported, which were of the vas-
From the clinical appearance, it is cular type. 9~‘7~19 difficult to differentiate the tumor from other mesenchymal tumors, such as fibroma, neurofibroma, lipoma, mucocele, or the malignant counterpart (leiomyosarcoma). Therefore, the diagnosis of leiomyoma in oral cavity is mainly determined by histologic study. It is sometimes difficult to differentiate leiomyoma from a neurilemmona, neurofibroma, or other spindle cell tumors such as spindle cell pleomorphic adenoma or a well-differentiated leiomyosarcoma. Only by evaluation with some special stains to identify collagen and muscle such as Van Gieson’s, Masson’s trichrome, and Mallory’s PTAH can a positive diagnosis be reached. In Masson’s trichrome staining, the smooth muscle stains red and the collagen fibers stain green or blue. Van Gieson’s stain has also been recommended by 01es2’ for staining muscle. However, these stains often gives a false-positive reaction for both collagen and muscle. To overcome this problem, Mallory’s PTAH stain can be used to prove the existence of myofibrils. In this case report, S-100 protein, Masson’s trichrome, and Mallory’s PTAH stains were used for differential diagnosis. The S-100 protein (a special stain for neural cells) was negative, indicating that the tumor was not of neural origin, whereas the tissues stained with Masson’s trichrome and Mallory’s PTAH stains tested positive. It is sometimes difficult to differentiate leiomyoma from a well-differentiated or low-grade leiomyosarcoma. Some authors suggest that the finding of mitoses is the most important feature in recognizing a leiomyosarcoma.2’*22 Ten mitotic figures per high-power field denote probable malignant behavior according to Robbins and Corten,23 whereas fewer then two mitoses per 10 high-power fields generally indicate a good prognosis according to Gorlin and Goldman.24 However, counting the number of mitoses in order to differentiate between benign and malignant lesions is not always reliable. There are some reports of smooth muscle tumor reported to be benign histologically which have locally invaded bone or metastasized to lymph nodes.25T26 The incidence of malignancy in oral smooth muscle tumors is proportionally higher compared with Table 2. Incidence of Types of Intraoral Leiomyoma Type Angioleiomyoma Solid leiomyoma Leiomyoblastoma Not recorded
No.
%
91 29 1 3
73 24
LEUNG. WONG, AND Ll
J Oral Maxillofac 481735-738.
Surg
1990
Oral Leiomyoma: Case Report KAM-WING LEUNG, DDS,* DANIEL YONG-KIE WONG, DDS, MS,t AND WING-YIN LI, DDS$
Leiomyoma is a benign tumor of smooth muscle origin that most often occurs in the uterus and gastrointestinal tract. It is seldom found in the oral cavity because of the paucity of smooth muscle. The earliest report of an oral leiomyoma was by Blanc’ in 1884. Since that time many other reports have appeared in the literature.2‘26 A 1986 literature review by Svane et al’ reported 116 cases of oral leiomyoma, including 30 from the Japanese literature.3 We have found 9 additional oral leiomyomas ,4-7 including the one in this article, making a total of 125 reports of intraoral leiomyomas (Table 1). This article describes a primary leiomyoma found in the lower buccal sulcus of a 26-year-old Chinese woman.
* Chief Resident and Clinical Instructor, Oral and Maxillofacial Surgery. Dental Department, Veterans General Hospital; and School of Dentistry, National Yang Ming Medical College, Taipei, Taiwan. t Lecturer and Attending Physician, Oral and Maxillofacial Surgery, Dental Department, Veterans General Hospital; and School of Dentistry, National Yang Ming Medical College, Taipei, Taiwan. $ Lecturer and Attending Physician, Pathology Department. Veterans General Hospital; and School of Medicine, National Yang Ming Medical College, Taipei, Taiwan. Address correspondence and reprint requests to Dr Wong: Division of Oral and Maxillofacial Surgery, Dental Department, Veterans General Hospital, VACRS, Taipei, Taiwan 11217, Republic of China. C 1990 American geons
Association
of Oral and Maxillofacial
Sur-
0278-2391190/4807-0013$3.0010 Table 1. No.
Report of a Case A nodular mass was found in the mandibular left buccal vestibule between the first and second molar region. It measured approximately 1.0 X 0.5 X 0.5 cm, and had been noticed by the patient for about 2 weeks (Fig 1). The lesion was shiny and firm, and the overlying mucosa was intact and smooth. There was no cervical lymph node enlargement. Panoramic and periapical radiographs of the involved region were taken and revealed no evidence of bony destruction. An excisional biopsy was performed in the outpatient department under local anesthesia. The biopsy report stated that the lesion was a leiomyoma and that the tumor had been incompletely excised. The patient was admitted to the hospital for a further surgical procedure. A wide excision in the previous biopsy site was performed under general anesthesia. The operation consisted of total removal of the residual tumor with surrounding mucosa and approximately 5 mm of the underlying muscle. The wound was closed primarily. The subsequent histology report showed the resected margin to be free of tumor. The surgical wound healed without complication. No tumor recurrence was noted at the l-year follow-up examination. The specimen consisted of a piece of grey-white soft tissue with covering mucosa measuring approximately 1.6 x 1.0 x 0.5 cm. The microscopic sections were composed of tumor cells arranged in a whorling and fascicular arrangement. No mitotic figures were seen (Fig 2). Irregular margins of the tumor with foci of expansive growth were evident. The S-100 protein was negative (Fig 3), whereas both Van Gieson’s and Masson’s trichrome stains were positive for muscle fibers (Fig 4), and the presence of myofibrils was confirmed using Mallory’s phosphotungstic acid-hematoxylin (PTAH) staining (Fig 5). The final diagnosis was solid leiomyoma of the buccal sulcus without signs of malignancy.
Nine New Cases of Intraoral Leiomyoma From 1996 to 1987 Author
Year
AgelSex
Site
Esguep and Sol& Esguep and Sola? Esguep and Sola Esguep and Sola? Esguep and Sola McMillian et al* Greenberg et aI6 Kawakami et al’ Leung et al
1986 1986 1986 1986 1986 1986 1987 1987 1987
48/F 47/M 50/M 42fM 24/F 54iM 73lM 33tM 26/F
Hard palate Lower lip Upper lip Soft palate Hard palate Central mandible Tonsil Lower lip Lower buccal sulcus
ORAL LEIOMYOMA:
FIGURE 1. Preoperative photograph showing tumor located in the buccal sulcus of first and second molar of left side of the mandible.
CASE REPORT
FIGURE 4. Masson’s trichrome-stained section shows the muscle cells stained red and collagen fiber stained blue. It is suggested that the tumor is of myogenous origin. (Original magnification, X400.)
Discussion
FIGURE 2. Photomicrograph of leiomyoma which is composed of spindle-shaped cells with blunt-ended nuclei arranged in whorling and fascicular arrangement. No mitotic fgmre is identified. (Hematoxylin-eosin stain. Original magnification, x 100.)
FIGURE 3. S-100 protein stain showed negative finding, suggesting that the tumor was not of neurogenic origin. (Original magnitication, X 100.)
Leiomyoma is rarely found in the oral cavity because of the relatively small amount of smooth muscle. In the experience of Farman and Kay,* based on 7,748 leiomyomas, approximately 95% occurred within the female genital tract, and only 5 (0.064%) were found in the oral cavity. Various authors have postulated different theories regarding the origin of leiomyoma in the oral cavity.9-‘3 Stout’ suggested that their origin was the smooth muscle of the tunica media of the blood vessel wall. Other sources were thought to be circumvallate papillae of the tongue, the submandibular duct, heterotopic embryonic muscle tissue, and the aberrant arrectors pilorum muscles in the cheek.‘0-13 According to the World Health Organization
FIGURE 5. Mallory’s PTAH-stained section shows the striated muscle stained red and smooth muscle cells stained orange. It is highly suggestive of smooth muscle origin. (Original magnification, x 100.)
737
LEUNG, WONG, AND LI
classification,‘4 there are three types of leiomyomas: leiomyomas (solid), angiomyoma (vascular leiomyoma), and epitheloid leiomyoma (leiomyoblastoma). Microscopically, the solid leiomyoma is a well-circumscribed tumor that is not associated with a blood vessel and which consists of intertwining spindle cells with varying amounts of collagen. The collagen may become so prominent as to obscure the true nature of the lesion. The muscle nuclei are elongated, blunted, and do not readily stain. The bundles of fibers usually form whorls because they are cut in different planes. Intracytoplasmic myofibrils can be demonstrated with special stains. Mitoses are usually rare. Vascular leiomyomas are associated with blood vessels from which they may derive their origin from the smooth muscle of the tunica media. They have a thick wall with a small rounded or stellate lumen, which often contains red blood cells. The smooth muscle fibers of the vessels are circularly disposed about the lumen and are associated with collagen fibers. Many of the vessels do not have muscular walls, only an endothelial lining. The leiomyoblastoma is composed of rounded or polygonal cells with a clear zone around the nucleus and an acidophilic cytoplasm. Smooth muscle fibers are rarely found. l4 From an extensive review of the literature, it was found that 74% of oral leiomyomas previously reported were angioleiomyomas, and 25% were solid leiomyomas. Only one case of leiomyoblastoma has been reported2 (Table 2). This is probably due to the fact that the main source of smooth muscle in the mouth is the blood vessel wall. The most common sites of oral leiomyomas are the lips (24.4%), followed by the palate (21.1%), tongue (19.5%), and cheek (16.3%) (Table 3). The sex ratio of reported cases is approximately about I: 1, with 63 males and 55 females. The patients’ ages ranged from infancy to 85 years with a mean age of 46 years. The greatest incidence occurred between 40 and 59 years of age (Table 4). Clinically, oral leiomyomas usually grow slowly, are painless superficial lesions, and often have a firm but elastic consistency. The tumor does not ulcerate and resembles normal mucosa in both color and texture. The size varies from a few millimeters to 3 cm. The majority of cases reported were asymptomatic. However, three lesions of the tongue reported by Blanc,’ Bertelli,” and Praal16 were painful. Other peculiar symptoms include a change in the patient’s voice, sore throat, difficulty in swallowing, and limitation of mouth opening. L,9,‘7*18 Recurrences are rarely seen after a normal follow-up period of 6 years. There were only three recurrences reported, which were of the vas-
From the clinical appearance, it is cular type. 9~‘7~19 difficult to differentiate the tumor from other mesenchymal tumors, such as fibroma, neurofibroma, lipoma, mucocele, or the malignant counterpart (leiomyosarcoma). Therefore, the diagnosis of leiomyoma in oral cavity is mainly determined by histologic study. It is sometimes difficult to differentiate leiomyoma from a neurilemmona, neurofibroma, or other spindle cell tumors such as spindle cell pleomorphic adenoma or a well-differentiated leiomyosarcoma. Only by evaluation with some special stains to identify collagen and muscle such as Van Gieson’s, Masson’s trichrome, and Mallory’s PTAH can a positive diagnosis be reached. In Masson’s trichrome staining, the smooth muscle stains red and the collagen fibers stain green or blue. Van Gieson’s stain has also been recommended by 01es2’ for staining muscle. However, these stains often gives a false-positive reaction for both collagen and muscle. To overcome this problem, Mallory’s PTAH stain can be used to prove the existence of myofibrils. In this case report, S-100 protein, Masson’s trichrome, and Mallory’s PTAH stains were used for differential diagnosis. The S-100 protein (a special stain for neural cells) was negative, indicating that the tumor was not of neural origin, whereas the tissues stained with Masson’s trichrome and Mallory’s PTAH stains tested positive. It is sometimes difficult to differentiate leiomyoma from a well-differentiated or low-grade leiomyosarcoma. Some authors suggest that the finding of mitoses is the most important feature in recognizing a leiomyosarcoma.2’*22 Ten mitotic figures per high-power field denote probable malignant behavior according to Robbins and Corten,23 whereas fewer then two mitoses per 10 high-power fields generally indicate a good prognosis according to Gorlin and Goldman.24 However, counting the number of mitoses in order to differentiate between benign and malignant lesions is not always reliable. There are some reports of smooth muscle tumor reported to be benign histologically which have locally invaded bone or metastasized to lymph nodes.25T26 The incidence of malignancy in oral smooth muscle tumors is proportionally higher compared with Table 2. Incidence of Types of Intraoral Leiomyoma Type Angioleiomyoma Solid leiomyoma Leiomyoblastoma Not recorded
No.
%
91 29 1 3
73 24
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