CLINICOPATHOLOGIC REVIEW : A Case of Palatal Pigmentation
Melanoma : Oral melanoma , while rare , is a serious disease that should be considered when any intraoral pigmentation is observed . 10 Oral melanoma is more prevalent in men and most often develops on the palate or gingiva , although it can affect any oral mucosal surface . 12 Most oral melanomas are of the acral lentiginous subtype , as opposed to the superficial spreading subtype most commonly seen on the skin . This is significant because acral lentiginous melanomas exhibit earlier onset of deep growth and connective tissue invasion , even while the surface appearance of the lesion appears flat and may seem innocuous . For cutaneous pigmented lesions , an ABCDE checklist is commonly used to evaluate for melanoma ( Asymmetry , Border irregularities , Color variation , Diameter greater than 6mm , and Evolving ).
Although these criteria can also be applied to assess intraoral lesions , it is important to note that they may be less reliable when evaluating oral lesions . When assessing oral pigmented lesions , bilaterality and symmetry are typically indicative of a benign process . Although irregular borders might increase a clinician ’ s level of suspicion for melanoma , benign melanocytic lesions of the oral cavity may also exhibit irregular borders . Color variation is also a common feature of oral melanoma and should be considered if observed . Oral melanomas are typically expansile lesions and the larger lesions often look ominous . However , small , innocuous appearing pigmented lesions of the oral cavity should not be discounted on this basis alone and may necessitate a biopsy to rule out melanoma . 1 , 11 Lastly , if the lesion is evolving or changing in size or appearance over time , a neoplastic process should be considered . Larger melanomas typically exhibit all of the ABCDE signs . In our case , the lesion was symmetrical in its outline and coloration , disfavoring a diagnosis of melanoma . An incisional biopsy was obtained that confirmed a benign process .
Leukemic infiltrate : Oral manifestations of leukemia may present in a variety of ways including ulcerations , spontaneous bleeding , gingival enlargement , or a soft tissue mass . Soft tissue enlargements are more frequently seen in patients with acute rather than chronic leukemia and are caused by infiltration of the connective tissue with malignant leukemic cells . In some instances , the enlarged tissue may exhibit a greenish discoloration , termed chloroma , that is linked to the presence of myeloperoxidase in the tumor infiltrate . Chloroma is typically associated with a subtype of acute myeloid leukemia ( AML ) that involves malignant transformation of granulocyte precursors . Our patient presented with a history of CML , not AML . Presentation of CML intraorally is rare , but gingival and mucosal swellings may be seen in the accelerated phase of the disease when the marrow is being displaced . 13 While our patient did have a history of CML , the symmetric pattern of palatal pigmentation without any mucosal swelling was not suggestive of a leukemic infiltrate . This was supported histologically by the absence of leukemic cells .
Tobacco-related discoloration : Tobacco-related pigmentation is most commonly referred to as “ smoker ’ s melanosis ” and is typically seen in heavy smokers . 14 The increase in melanin is thought to be reactive , brought on by the heat and / or noxious chemicals associated with smoking . 15 Smoker ’ s melanosis is most commonly observed on the anterior labial mandibular gingiva , although it may occur on other locations like the palate or maxillary gingiva . 7 It may present as multiple brown macules or a diffuse pigmentation of the mucosa . Tobacco-related pigmentation is considered a benign condition and it typically regresses with smoking cessation . 7 , 15
In our case , the patient reports a history of smokeless tobacco use only . While smokeless tobacco may cause a change in the color of the oral mucosa , it would be limited to the location where the patient places the smokeless tobacco . Smokeless tobacco use typically results in a diffuse , wrinkled , whitish appearance of the vestibular mucosa called tobacco pouch keratosis . 15 In our case , tobacco related discoloration can be clinically ruled out due to the location and appearance of the lesion , along with the fact that our patient does not report smoking . Histologically , the absence of melanin pigment within the basal cell layer does not support a diagnosis of tobacco-related pigmentation .
NOVEMBER / DECEMBER 2021 | PENNSYLVANIA DENTAL JOURNAL 19