A well-circumscribed lobulated tumor on the hard palatal mucosa in a child

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A well-circumscribed lobulated tumor on the hard palatal mucosa in a child

D1X XAlfonso Salcines,D2X XBS,aD3X XSook-Bin Woo,D4X XDMD, MMSc, FDSRCS (Edin),b,cD5X XVikki Noonan,D6X XDMD, DMSc,c,d D7X XMichael J. Mansfield,D8X XDMD,eandD9X XChia-Cheng Li,D10X XDDS, DMScb

(Oral Surg Oral Med Oral Pathol Oral Radiol 2019;127:3 7)

CLINICAL PRESENTATION

A 9-year-old Caucasian female presented with a non- tender, slow-growing mass on the right hard and soft palate, measuring 2.0£ 1.5 cm. On examination, the lesion presented as a well-circumscribed, soft tissue tumor with a lobulated appearance covered by normal- appearing oral mucosa (Figure 1). There was no ulcera- tion and no induration. Adjacent teeth were vital, and a source of infection was not identified. There was no pal- pable lymphadenopathy. Computed tomography images indicated that there was no bone erosion or tooth resorp- tion. The patient was healthy without any medical con- ditions and was not taking any medications.

An incisional biopsy was performed and the speci- men was evaluated histopathologically. Three years after the incisional biopsy, the patient returned because the mass continued to expand. The patient did not report any pain or paresthesia. Medical history was unremarkable and she was not taking any medica- tions. On examination, the lesion exhibited a lobu- lated appearance and was covered by normal- appearing mucosa without evidence of pigmentation or ulceration. The lesion appeared to have an increased size and measured 2.5£ 1.5 cm. The lesion was excised, and there was no involvement of the underlying bone.

DIFFERENTIAL DIAGNOSIS

A slow-growing, lobulated, and firm palatal soft tissue mass in a child elicits an extensive differential diagnosis.

The lack of symptoms and multilobulated appearance of

the lesion without significant radiographic findings ruled out an infectious etiology. The mass was confined mostly to the hard palatal mucosa and did not invade the under- lying bone, and as such, central odontogenic tumors and primary osseous pathologic conditions were excluded.

Peripheral odontogenic tumors were unlikely because the location of the tumor was centered around the midpa- latal mucosa rather than the gingival margin. Our differ- ential diagnosis was focused on salivary gland and soft tissue tumors.

The palatal mucosa is the most common location for minor salivary gland neoplasms.1Salivary gland neo- plasms are rare in the pediatric population, and the mean age of occurrence is 15.1 years.2The most com- mon benign salivary gland neoplasm in pediatric patients is pleomorphic adenoma (70.6% of all salivary gland neoplasms), appearing as a slow-growing, pain- less, and firm mass.1,2Mucoepidermoid carcinoma, the most common salivary gland malignancy in children (13.4% of all salivary gland neoplasms), was also a consideration.1,2 Low-grade salivary gland malignan- cies are slow growing and may appear innocuous or present with surface epithelial papillary hyperplasia.3

Due to the indolent growth pattern over a few years, we focused on benign mesenchymal neoplasms.

Benign peripheral nerve sheath tumors (e.g., neurofi- broma, schwannoma, and solitary circumscribed neu- roma) are the most common soft tissue tumors in the oral cavity, and the hard palatal mucosa is a common intraoral site.4 These tumors typically present as a Fig. 1. A well-circumscribed, firm tumor with a lobulated appearance covered by normal oral mucosa, measuring 2.0£ 1.5 cm, was present on the hard palatal mucosa without evidence of pigmentation.

The case report was presented as a poster at the 2017 American Academy of Oral and Maxillofacial Pathology annual meeting, New- port, Rhode Island.

aHarvard School of Dental Medicine, Boston, Massachussetts, USA.

bDepartment of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, Massachussetts, USA.

cCenter for Oral Pathology, StrataDx, Lexington, Massachussetts, USA.

dDepartment of Oral and Maxillofacial Surgery, Division of Oral Pathology, Boston University Henry M. Goldman School of Dental Medicine, Boston, Massachussetts, USA.

ePrivate practice, Glendale, Arizona, USA.

Received for publication Jul 6, 2017; returned for revision Nov 24, 2017; accepted for publication Dec 2, 2017.

Ó 2017 Elsevier Inc. All rights reserved.

2212-4403/$-see front matter

http://doi.org/10.1016/j.oooo.2017.12.002

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slow-growing, firm, smooth-surfaced, and painless nodule or diffuse mass covered by normal mucosa, whereas the tumor in our case was multilobulated.4 Benign peripheral nerve sheath tumors may arise at any age and are usually solitary lesions. When multi- ple, syndromes such as neurofibromatosis or multiple endocrine neoplasia should be considered.4

Other benign mesenchymal neoplasms, such as those of myofibroblastic, muscular, and adipocytic origin, were also considered. Myofibroblastic tumors, such as myofibroma and nodular fasciitis, are in the differential diagnosis. Myofibroma is a benign spindle cell tumor consisting of myofibroblasts with a predilection for the head and neck region, and 8% of myofibromas occur on the palatal mucosa.5Myofibroma commonly occurs in children or young adults (mean age 21.7 years), pre- senting as a firm, painless, rapidly enlarging mass, and it sometimes can be mistaken for a malignant tumor because of rapid enlargement.5Recurrence is noted in 10% of cases.5Nodular fasciitis, a clonal proliferation of myofibroblasts associated with USP6 gene rear- rangement, also typically exhibits a clinical history of rapid growth and presents as a nodule or mass.6,7 Although nodular fasciitis mainly arises in young adults, more than half of the intraoral counterparts (58%) develop between the fourth to fifth decade of life.6

Congenital hamartomatous lesions (i.e., leiomyom- atous hamartoma) and benign myocytic neoplasms (e.g., leiomyoma and rhabdomyoma) are also included in our differential diagnosis. Leiomyoma- tous hamartoma is a benign, self-limiting proliferation of smooth muscle cells that typically occurs in the first year of life.8It is a rare entity in the oral cavity; hard palatal mucosa and tongue are the most common intraoral locations.8Leiomyomatous hamartoma typi- cally presents as a pedunculated or polypoid mass with an indolent nature, similar to our present case.8 Leiomyoma is a benign tumor of mature smooth mus- cle cells, predominantly occurring in the uterus, gas- trointestinal tract, and skin.9 Intraoral counterparts are uncommon, typically occurring on the lips or pala- tal mucosa, with 75% representing angioleiomyoma (vascular leiomyoma).9,10Leiomyoma usually occurs in the fourth to fifth decade with a slight female predi- lection and presents as a firm, slow-growing, painless mass covered by normal oral mucosa.9 Rhabdo- myoma is a benign neoplasm of mature striated mus- cle cells with a predilection for the head and neck region.11Of the two subtypes of head and neck rhab- domyoma, adult rhabdomyoma is more prevalent in middle-aged male patients (4:1 male:female) in the seventh decade with a mean age 60 years (range 33- 80), whereas fetal rhabdomyoma occurs in pediatric patients, with the oral cavity as one of the common

sites.12,13Clinically, intraoral rhabdomyoma appears as an asymptomatic, solitary or multinodular mass and is commonly found in the floor of mouth, soft pal- ate, and base of tongue.12

Lipoma, a benign tumor of mature adipose tissue, typically presents as a solitary, soft, asymptomatic nod- ule.14 Intraoral lipomas tend to occur on the buccal mucosa and buccal vestibule, with the palatal mucosa being the least common site; children are rarely affected.14Other tumors such as solitary fibrous tumor are less common, and vascular tumors would tend to have a bluish hue. Finally, the palatal mucosa is a com- mon site of occurrence for lymphoma, and some can be low grade and slow growing. However, this is uncommon in patients in the first decade of life.

DIAGNOSIS AND MANAGEMENT

An excision was performed and the histopathologic results were compared with the original biopsy speci- men. Both specimens had benign epithelial hyperplasia with an undulated surface and elongated, intercon- nected rete ridges (Figure 2 A and B). The mass was composed of a dense diffuse infiltrate of small epitheli- oid melanocytes that filled and expanded the deep lam- ina propria; some of the melanocytes had hyperchromatic nuclei (Figure 2 B-D). These melano- cytes were arranged in clusters, theques, or bands, streaming through collagen bundles with only focal melanin deposition (Figure 2 C-E). Focal junctional activity was noted (Figure 2 E). Melanocytes were present adjacent to the vessel walls or within the ductal epithelium (Figures 2 C and 3 C). There was mild vari- ation in nuclear shape and size, but mitoses were not identified. The majority of the melanocytes had cyto- plasmic positivity for MART-1 (Figure 3 A) and nuclear and cytoplasmic positivity for p16 (Figure 3 B and C), with a small population of cells in the junc- tional component and just beneath the epithelium hav- ing cytoplasmic positivity for HMB-45. MIB-1 labeling index was <5% (Figure 3 A). The palatal mass was diagnosed as intraoral congenital melano- cytic nevus (CMN). No recurrence was reported at 1 year follow-up.

DISCUSSION

CMN consists of a benign proliferation of melano- cytes at birth or shortly after birth.15 Compared with acquired cutaneous melanocytic nevi, cutaneous CMNs are usually larger with variation in color, shape, and clinical morphologic characteristics.15 CMN is not an uncommon entity on the skin with an estimated prevalence of 0.5%-31.7%.15 The clinical appearance of cutaneous CMN may change with age;

initially it commonly presents as a pigmented mac- ule.15 Cutaneous CMN can be further categorized

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based on size into small (<1.5 cm), medium (1.5- 19.9 cm), and large/giant (>20.0 cm) lesions.15 Most cutaneous CMN are medium in size, and giant CMN are far less common.15 N-Ras mutations have been identified in many CMNs, whereas melanoma typi- cally harbors B-RAF mutations.15

Intraoral CMN is extremely rare, with only six cases reported in the English literature.16-21Two of these six

articles did not provide a complete clinical and histo- pathologic description of the intraoral CMN and were excluded from the following discussion.17,19 Including our present case, all intraoral CMN occurred in female patients, with all cases noted within the first two decades of life (Table I).16,18,20,21One case occurred on the pala- tal mucosa as in this case.20Clinically, all the previous reports of intraoral CMN had either uniform or scattered Fig. 2. (A) Undulated epithelial hyperplasia with many epithelioid melanocytes expanding and filling the lamina propria (hema- toxylin-eosin [H&E],£20). (B) Dense diffuse infiltration of melanocytes in the lamina propria. The majority of the melanocytes were epithelioid with some exhibiting hyperchromatic nuclei. The overlying mucosa exhibited a lobulated configuration with elongated, irregularly interconnected rete ridges (H&E,£100). (C) The melanocytes with focal melanin deposition were present adjacent to the vessel wall (H&E,£400). A high-resolution version of this slide for use with the Virtual Microscope is available as eSlide:VM04601. (D) Some epithelioid melanoctyes formed strands and bands, streaming between collagen bundles. There was minimial melanin deposition in the melanocytes (H&E,£400). A high-resolution version of this slide for use with the Virtual Microscope is available as eSlide:VM04601. (E) Focal junctional activity with nested melanocytes (H&E, £400). A high-resolu- tion version of this slide for use with the Virtual Microscope is available as eSlide:VM04601.

Fig. 3. (A) The majority of the melanocytes had cytoplasmic positivity for MART-1 (red), and MIB-1 labeling index was < 5%

(brown) (£200). A high-resolution version of this slide for use with the Virtual Microscope is available as eSlide:VM04603. (B) The melanocytes exhibited nuclear and cytoplasmic positivity for p16 (£200). A high-resolution version of this slide for use with the Virtual Microscope is available as eSlide:VM04605. (C) The melanocytes were positive for p16, and some melanocytes were present in the ductal epithelium (£200). A high-resolution version of this slide for use with the Virtual Microscope is available as eSlide:VM04605.

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pigmentation, with a nodular, polypoid, or plaquelike appearance, and measured 0.7-5.0 cm.16,18,20,21

How- ever, in our present case, there was no clinical pigmenta- tion and only minimal pigmentation on histopathologic examination. Including the present case, no recurrence has been reported after surgical removal.16,18,20,21

Histopathologically, intraoral CMN is a well-cir- cumscribed nodule with a papillomatous or polypoid configuration, consisting of a proliferation of melano- cytes with a nested and diffuse pattern exhibiting downward maturation.21 There is variable melanin deposition and a lack of mitotic figures in melanocytes, and up to 30% of cutaneous CMNs have been reported with cytologic atypia in melanocytes.15,21 Junctional activity or involvement of vessel walls or salivary ducts can be present, as in the present case. In addition to histopathologic evaluation, immunohistochemical studies can distinguish congenital nevus from mela- noma. Melanocytes in CMN are positive for MART-1 and p16 but negative or minimally positive for HMB-45. MIB-1 positivity is present in less than 5%

of the melanocytes in the superficial lamina propria, in keeping with its benign nature.21,22

On the skin, CMN may be associated with the devel- opment of melanoma, although the relative risk of developing a melanoma from an existing CMN varies from study to study.23Larger size and the presence of satellite CMN are correlated with malignant transfor- mation.15 Neuromelanosis (cerebral melanosis) is a congenital abnormality with melanocytic proliferation in the leptomeninges and brain parenchyma. It is termed neurocutaneous melanosis (NCM) when neuro- melanosis is associated with a CMN.24NCM may lead to various clinical symptoms, such as headache, vomit- ing, photophobia, and seizures.24There is a well-estab- lished association between NCM and giant CMN, with NCM occurring in 2.5%-45% of patients with cutane- ous giant CMN.15 However, this association has not

been noted in intraoral CMN. In addition, mucosal nevi are associated with 31% of large cutaneous CMNs.15

Excision is the first-line treatment for CMN; how- ever, the efficacy of reducing malignant transformation is still not proven.25 Lifelong surveillance for recur- rence or development of malignant melanoma is recommended.25

REFERENCES

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Oral Oncol. 2007;43:463-470.

2. Deng R, Huang X, Hao J, Ding J, Hu Q. Salivary gland neo- plasms in children. J Craniofac Surg. 2013;24:511-513.

3. Chi AC, Neville BW. Surface papillary epithelial hyperplasia (rough mucosa) is a helpful clue for identification of polymor- phous low-grade adenocarcinoma. Head Neck Pathol. 2015;9:

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Table I. Clinical features of the intraoral CMN reported in the English literature

Authors Age Gender Location Clinical features Management Follow-up

Takeda16 7 F Labial mucosa Brownish-black, firm nodule present since birth and had not changed in size or color, 0.7£ 0.7 cm

Excision No recurrence after 3 years

Allen and Pellegrini18

3 F Posterior mandibular ginigva

Sharply demarcated, slightly elevated, dark brown plaque, 0.8£ 1.5 cm

Excision No recurrence after 6 months Gilbert et al.20 19 F Hard palatal mucosa Well-demarcated plaque with a slightly

pebbled texture, 1.2£ 1.1 £ 0.3 cm

Excision Patient failed to return for follow-up Marangon et al.21 16 F Buccal mucosa Diffuse swelling with papular surface,

scattered pigmentation and ill-defined border, 5.0£ 4.0 cm

Incision No recurrence after 11 years

Present case 9 F Hard palatal mucosa Well circumscribed, lobulated tumor covered by normal oral mucosa with no pigmentation, 2.5£ 1.5 cm

Partial excision, followed by excision

No recurrence after 1 year

CMN, congenital melanocytic nevus.

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11. Parara E, Christopoulos P, Tosios K, Paravalou I, Vourlakou C, Alexandridis K. A swelling of the floor of the mouth. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2010;109:12-16.

12. Kapadia SB, Meis JM, Frisman DM, Ellis GL, Heffner DK, Hyams VJ. Adult rhabdomyoma of the head and neck: a clinico- pathologic and immunophenotypic study. Human Pathol.

1993;24:608-617.

13. Kapadia SB, Meis JM, Frisman DM, Ellis GL, Heffner DK. Fetal rhabdomyoma of the head and neck: a clinicopathologic and immunophenotypic study of 24 cases. Human Pathol.

1993;24:754-765.

14. Furlong MA, Fanburg-Smith JC, Childers EL. Lipoma of the oral and maxillofacial region: site and subclassification of 125 cases.

Oral Surg Oral Med Oral Pathol Oral Radiol Endod.

2004;98:441-450.

15. Alikhan A, Ibrahimi OA, Eisen DB. Congenital melanocytic nevi: where are we now? Part I. Clinical presentation, epidemiol- ogy, pathogenesis, histology, malignant transformation, and neu- rocutaneous melanosis. J Am Acad Dermatol. 2012;67:e1-e17..

quiz 512-514.

16. Takeda Y. Congenital nevocellular nevus of the oral mucosa.

Ann Dent. 1988;47:40-42.

17. Buchner A, Leider AS, Merrell PW, Carpenter WM. Melano- cytic nevi of the oral mucosa: a clinicopathologic study of 130 cases from northern California. J Oral Pathol Med.

1990;19:197-201.

18. Allen CM, Pellegrini A. Probable congenital melanocytic nevus of the oral mucosa: case report. Pediatr Dermatol. 1995;12:145-148.

19. Rose C, Kaddu S, El-Sherif TF, Kerl H. A distinctive type of widespread congenital melanocytic nevus with large nodules. J Am Acad Dermatol. 2003;49:732-735.

20. Gilbert ML, Hanna W, Ghazarian D, Dover D, Klieb HB. Con- genital melanocytic nevus of the oral mucosa: report of a rare pigmented lesion and review of the literature. Clin Pract.

2011;1:e17.

21. Marangon Junior H, Souza PE, Soares RV, de Andrade BA, de Almeida OP, Horta MC. Oral congenital melanocytic nevus: a rare case report and review of the literature. Head Neck Pathol.

2015;9:481-487.

22. Kaleem Z, Lind AC, Humphrey PA, et al. Concurrent Ki-67 and p53 immunolabeling in cutaneous melanocytic neoplasms: an adjunct for recognition of the vertical growth phase in malignant melanomas? Modern Pathol. 2000;13:217-222.

23. Krengel S, Hauschild A, Schafer T. Melanoma risk in congenital melanocytic naevi: a systematic review. Br J Dermatol.

2006;155:1-8.

24. Kadonaga JN, Frieden IJ. Neurocutaneous melanosis: definition and review of the literature. J Am Acad Dermatol. 1991;24:

747-755.

25. Ibrahimi OA, Alikhan A, Eisen DB. Congenital melanocytic nevi: where are we now? Part II. Treatment options and approach to treatment. J Am Acad Dermatol. 2012;67:e1-e13.. quiz 28-30.

Reprint requests:

Chia-Cheng Li, DDS, DMSc

Department of Oral Medicine, Infection, and Immunity Harvard School of Dental Medicine

188 Longwood Avenue Boston, MA 02115 USA

Chia-Cheng_Li@hsdm.harvard.edu

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