CLINICOPATHOLOGIC REVIEW :
A Case of Palatal Pigmentation By Grayson Cole , DDS and Joanne Prasad , DDS , University of Pittsburgh School of Dental Medicine
CLINICAL HISTORY
A 39-year-old white male presented to an oral and maxillofacial surgeon with an asymptomatic , diffuse , blue-gray to black discoloration of the hard palate of at least two years duration . The coloration was darkest and most intense in the palatal vault , with some lateral attenuation . The lesion demonstrated symmetry of outline and color about the palatal midline . There was no thickening or enlargement of the soft tissue and the surface mucosa appeared intact , without any signs of ulceration ( Figure 1 ).
The patient ’ s medical history was significant for type 1 diabetes , managed with a fast-acting and a long-acting insulin ( Humalog ® and Toujeo SoloStar ®, respectively ). In addition , the patient revealed a history of chronic myeloid leukemia , treated with the chemotherapeutic drug imatinib ( Gleevec ®) for the past 11 years . The patient ’ s social history was significant for long-cut smokeless tobacco use .
What is the most likely diagnosis ? A . Physiologic pigmentation B . Melanoma C . Leukemic infiltrate D . Drug-related pigmentation E . Tobacco-related discoloration
FIGURE 1
FIGURE 2
An incisional biopsy of the lesion was obtained . Histologic examination of the specimen revealed stratified squamous epithelium overlying dense irregular fibrous connective tissue . Deposits of small dark-brown spherical granules were noted within the connective tissue stroma . The pigmented particles were observed along the length of collagen fibers and clinging to the cytoplasmic extensions of spindled fibroblasts ( Figure 2 ). In areas , some particles were noted adjacent to small blood vessels , but the perivascular deposition was not pronounced .
Multinucleated giant cells were not observed .
The basal epithelial cells were notably devoid of melanin pigment and the underlying connective tissue did not contain any melanocytes , nevus cells , or leukemic cells ( Figure 3 ). Melanoma , physiologic pigmentation , melanosis , and leukemic infiltration of oral soft tissues were ruled out , given these microscopic observations . The histologic findings were determined to be consistent with medication-induced pigmentation .
FIGURE 3
NOVEMBER / DECEMBER 2021 | PENNSYLVANIA DENTAL JOURNAL 17