Polymorphous Low Grade Adenocarcinoma

In 1983 two separate investigations reported on low-grade adenocarcinomas of minor salivary glands referred to as "terminal duct carcinoma" (Batsakis, Pinkston, and Luna et al. 1983) and "lobular carcinoma" (Freedman and Lumerman 1983). Terminal duct carcinoma was suggested to specify the histogenesis of the tumor, which was thought to be the progenitor cell of the terminal duct. Lobular carcinoma was suggested due to the morphology of the tumor resembling lobular carcinoma of the breast. A review of these reports indicates that the authors were independently describing the same neoplasm (Wenig and Gnepp 1991). It is thought that, prior to this time, these neoplasms were classified as either adenoid cystic carcinoma or adenocarcinoma (Regezi et al. 1991). High-power evaluation of polymorphous low-grade adenocarcinoma and adenoid cystic carcinoma may permit the distinction between the two malignancies, as adenoid cystic carcinoma shows ductal-type structures lined by multiple cells in thickness, while polymorphous low-grade carcinoma shows ductal-type structures more commonly lined by single cell layers (Figure 10.10). An Indian filing pattern is also seen in polymorphous low-grade adenocarcinoma. The common morphologic features of polymorphous low-grade adenocarcinoma and adenoid cystic carcinoma have led researchers to investigate methods of distinguishing these diagnoses (Beltran et al. 2006). In 1984 Evans and Batsakis described 14 cases of a distinctive minor salivary gland neoplasm that they named "polymorphous low-grade adenocarcinoma." This term emphasized the features of this neoplasm, including its cytologic uniformity and histologic diversity, variable growth patterns from solid to papillary to cribriform to fascicular, and relative lack of nuclear atypia (Evans and Batsakis 1984). Mitotic

Figure 10.8a. An indurated upper lip mass that was fixed to the surrounding mucosa.

Figure 10.8c. A wide local excision of the mass with oral mucosal sacrifice observing 1 cm linear margins was planned.

Figure 10.8b. Due to the likely but equivocal malignant nature of the mass, incisional biopsy is essential for the establishment of the diagnosis prior to definitive surgical therapy. The histopathology of the incisional biopsy identified intermediate-grade mucoepidermoid carcinoma.

Figure 10.8d. A surgical plane was developed between the dermis of the upper lip and the musculature on the deep aspect of the tumor specimen.

Figure 10.8e. The specimen was delivered and oriented Figure 10.8g. The defect was reconstructed immediately for the pathologist with sutures. with a full thickness skin graft.

Figure 10.8f. Final histopathology identified intermediate-grade mucoepidermoid carcinoma with perineural invasion.

Figure 10.8h. A prophylactic neck dissection was not performed as part of this cancer surgery due to the low concern for occult neck disease associated with this diagnosis. The patient underwent postoperative radiation therapy and the surgical site was noted to be well healed at 1 year postoperatively without signs of recurrent disease. Reprinted with permission from Carlson ER. 1995. Salivary gland pathology—clinical perspectives and differential diagnosis. In: The Comprehensive Management of Salivary Gland Pathology, Oral and Maxillofacial Surgery Clinics of North America 7. Philadelphia: W.B. Saunders, pp. 361-386.

Figure 10.8h. A prophylactic neck dissection was not performed as part of this cancer surgery due to the low concern for occult neck disease associated with this diagnosis. The patient underwent postoperative radiation therapy and the surgical site was noted to be well healed at 1 year postoperatively without signs of recurrent disease. Reprinted with permission from Carlson ER. 1995. Salivary gland pathology—clinical perspectives and differential diagnosis. In: The Comprehensive Management of Salivary Gland Pathology, Oral and Maxillofacial Surgery Clinics of North America 7. Philadelphia: W.B. Saunders, pp. 361-386.

Figure 10.9a. A 52-year-old man with a 6-month history of a palatal mass.

Figure 10.9b. Incisional biopsy showed adenoid cystic carcinoma.

Figure 10.9c. Computerized tomograms identified a soft tissue mass and minimal invasion of the palatal bone.

Figure 10.9d. A maxillectomy was planned for this patient observing 1 cm linear margins in bone and soft tissue.

Figures 10.9e and 10.9f. The bony cuts were created throughout the maxilla and the Smith Ramus Separator (Walter Lorenz Surgical, a Biomet Company, Jacksonville, Florida) (e) was utilized to separate the specimen from the remaining facial skeleton (f).

Figure 10.9g. The specimen was delivered and inspected from the palatal side so as to clinically confirm the efficacy of the resection.

Figure 10.9h. The specimen was also inspected from the nasal/sinus side so as to confirm the adequacy of the resection.

Figure 10.9i. Frozen sections were obtained to microscopically examine the soft tissue margins as well as a segment of the greater palatine nerve in the superior aspect of the defect near foramen rotundum. All frozen sections were negative, thereby not requiring additional sampling of the nerve or mucosa. The final decalcified histopathology showed the tumor invading the maxillary bone.

Figure 10.9i. Frozen sections were obtained to microscopically examine the soft tissue margins as well as a segment of the greater palatine nerve in the superior aspect of the defect near foramen rotundum. All frozen sections were negative, thereby not requiring additional sampling of the nerve or mucosa. The final decalcified histopathology showed the tumor invading the maxillary bone.

Figure 10.9j. The patient underwent postoperative radiation therapy and showed no evidence of cancer at 1 year postoperatively. This view provides anatomic delineation of the eustachian tube in the defect.

Figures 10.10a and 10.10b. Subtle differences between the adenoid cystic carcinoma (a) and the polymorphous low-grade adenocarcinoma (b). The adenoid cystic carcinoma characteristically shows multiple cell layered ductal structures, while the polymorphous low-grade adenocarcinoma shows single cell layered ductal structures. Reprinted with permission from Carlson ER. 1995. Salivary gland pathology—clinical perspectives and differential diagnosis. In: The Comprehensive Management of Salivary Gland Pathology, Oral and Maxillofacial Surgery Clinics of North America 7. Philadelphia: W.B. Saunders, pp. 361-386.

Figures 10.10a and 10.10b. Subtle differences between the adenoid cystic carcinoma (a) and the polymorphous low-grade adenocarcinoma (b). The adenoid cystic carcinoma characteristically shows multiple cell layered ductal structures, while the polymorphous low-grade adenocarcinoma shows single cell layered ductal structures. Reprinted with permission from Carlson ER. 1995. Salivary gland pathology—clinical perspectives and differential diagnosis. In: The Comprehensive Management of Salivary Gland Pathology, Oral and Maxillofacial Surgery Clinics of North America 7. Philadelphia: W.B. Saunders, pp. 361-386.

figures were infrequent and tumor necrosis was only seen in 1 case. Perineural invasion was and continues to be commonly noted in this malignancy. The tumors were distinctly unencapsulated and deeply infiltrative of bone and surrounding soft tissues. Radical surgical procedures were required for tumor control, but no distant metastases were noted. The authors judged from their survey of adenocarcinomas of the major salivary glands that the polymorphous low-grade adenocar-

cinoma was at least primarily an oral neoplasm. Since this report, Batsakis and El-Naggar (1991) have subclassified polymorphous low-grade ade-nocarcinomas (terminal duct adenocarcinomas) into papillary and nonpapillary forms. The papillary form was found to exhibit a more aggressive course with a higher rate of recurrence at the primary site, metastasis to cervical lymph nodes, and distant metastasis. The AFIP registry identified 75 cases of this neoplasm, and all were located in the minor salivary glands (Wenig and Gnepp 1991). Forty-four of these cases were located in the palate (58.6%), with the upper lip and buccal mucosa showing 12 cases each. Involvement of other oral minor salivary gland sites has been reported; however, this is quite rare (de Diego et al. 1996; Kennedy et al. 1987).

Since its original description in minor salivary gland sites, cases of polymorphous low-grade ade-nocarcinoma have been reported in the parotid gland, such that this tumor cannot be stated to be exclusive to minor salivary gland tissue (Barak, Grobbel, and Rabaja 1998; Merchant, Cook, and Eveson 1996).

Treatment of polymorphous low-grade ade-nocarcinoma requires surgery with curative intent. The surgical procedure is based on the anatomic site. Surgical removal of these tumors in the palate requires a thorough assessment of the palatal bone with computerized tomograms. Bone involvement by this tumor is not an inherent property of this neoplasm but rather a function of chronicity of the tumor. Since these malignancies are not fast growing, many patients have long histories of their presence, such that palatal bone infiltration by the tumor may occur over time. In addition, the characteristically deeply infiltrative nature of these tumors into surrounding soft tissues, regardless of the chronicity of the tumor, is such that the soft palate typically requires full thickness sacrifice in most cases. These features are clearly a departure from the treatment of mucoepidermoid carcinoma of the palate, where grade is the main determining factor in planning surgical treatment. Once a biopsy diagnosis of polymorphous low-grade adenocarci-noma of the palate has been established, therefore, CT scans should be obtained to examine the quality of the palatal bone. If the bone is unaltered by the tumor, a bone-sparing, periosteal sacrificing wide local excision with full thickness sacrifice of the soft palate may be performed (Figure 10.11). Due to the tumor's neurotropism, the greater palatine a b

Figure 10.11a. A 51-year-old man with a mass of the soft palate that had reportedly been present for only 2 months.

Figure 10.11d. A Dingman mouth gag (Walter Lorenz Surgical, a Biomet Company, Jacksonville, Florida) was utilized so as to provide acceptable retraction to perform this surgery.

Figures 10.11b and 10.11c. Incisional biopsy showed a microscopically cribriform tumor with obvious perineural invasion. A diagnosis of polymorphous low-grade adeno-carcinoma was made. Computerized tomograms did not reveal involvement of the palatal bone such that a periosteal sacrificing, bone-sparing wide local excision with full thickness sacrifice of the soft palate was performed.

Figure 10.11e. One-centimeter linear margins in mucosa were planned.

Figure 10.11f. The specimen is delivered.

Figure 10.11g. Final histopathology identified a negative periosteal surface, thereby justifying the preservation of palatal bone.

Figure 10.11h. The greater palatine neurovascular bundle was clamped prior to delivery of the specimen so as to procure a 1 cm segment of nerve for frozen section analysis. The hemostat remained on the nerve stump while the frozen section was being evaluated, which was negative for cancer. If the nerve had been positive for cancer, the nerve would have been pulled down to procure additional frozen sections so as to clear the cancer.

Figure 10.11h. The greater palatine neurovascular bundle was clamped prior to delivery of the specimen so as to procure a 1 cm segment of nerve for frozen section analysis. The hemostat remained on the nerve stump while the frozen section was being evaluated, which was negative for cancer. If the nerve had been positive for cancer, the nerve would have been pulled down to procure additional frozen sections so as to clear the cancer.

Figures 10.11i, 10.11j, and 10.11k. The defect (i) was addressed with an immediate obturator that had been fabricated preoperatively (j) and was placed intraopera-tively (k).

Figure 10.111. The exposed palatal bone is covered with Figure 10.11n. At 1 year postoperatively, the patient's immature granulation tissue at 1 month postoperatively. defect has demarcated well.

Figure 10.11m. Immature granulation tissue underwent maturation by 3 months postoperatively as seen in this image.

Figure 10.11o. A definitive obturator has been fabricated. Reprinted with permission from Carlson ER. 1995. Salivary gland pathology—clinical perspectives and differential diagnosis. In: The Comprehensive Management of Salivary Gland Pathology, Oral and Maxillofacial Surgery Clinics of North America 7. Philadelphia: W.B. Saunders, pp. 361-386.

neurovascular bundle should be sampled for frozen sections superiorly. Since perineural spread is not characteristic of this tumor, it is unlikely to find tumor tracking along the nerve, in contradistinction to adenoid cystic carcinoma, where tumor may be found surrounding this nerve at foramen rotundum. An immediate surgical obturator is fabricated preoperatively for insertion at the time of ablative surgery so as to permit the patient to begin taking a diet on the day of surgery. If the bone is eroded by the tumor, a traditional maxillectomy is necessary, also resulting in a full thickness sacrifice of the soft palate (Figure 10.12). An immediate surgical obturator must also be fabricated preop-eratively for insertion at the time of surgery when a maxillectomy is planned for this diagnosis.

Figure 10.12a. A biopsy-proven polymorphous low-grade adenocarcinoma of the palate in a 53-year-old woman that had been present for several years, according to the patient.

Figure 10.12c. A maxillectomy was performed, observing 1 cm linear margins in bone and soft tissue.

Was this article helpful?

0 0
10 Ways To Fight Off Cancer

10 Ways To Fight Off Cancer

Learning About 10 Ways Fight Off Cancer Can Have Amazing Benefits For Your Life The Best Tips On How To Keep This Killer At Bay Discovering that you or a loved one has cancer can be utterly terrifying. All the same, once you comprehend the causes of cancer and learn how to reverse those causes, you or your loved one may have more than a fighting chance of beating out cancer.

Get My Free Ebook


Post a comment