DIFFERENTIAL DIAGNOSIS A. Squamous Papilloma Squamous papilloma is a benign lesion typically caused by HPV types 6 and 11, which is commonly seen in the posterior oral cavity.
[ 5 ]
The clinical presentation of this case favored squamous papilloma; however, only by submission of the specimen to oral pathologist was the correct diagnosis identified. Commonly found on the palate and tongue, these lesions are usually pedunculated, with a cauliflower-like appearance, and rarely exceed 5 mm. [ 5 ] In this case, although the lesion exhibited papillary architecture, histopathologic findings excluded squamous papilloma.
B. Papillary Squamous Cell Carcinoma( P-SCC) A rare variant of squamous cell carcinoma, P-SCC is more common in the larynx but can involve any part of the aerodigestive tract. [ 6 ] P-SCC is associated with smoking, alcohol use, and possibly high-risk HPV infection. [ 6 ] Histologically, P-SCC exhibits papillary growth with a less-distinct fibrovascular core. [ 5 ] Features include nuclear pleomorphism, frequent mitotic activity, and possible invasion beyond the basement membrane. [ 5 ]
In this case, cytokeratin markers( CAM5.2, cytokeratin AE1 / 3) failed to stain invasive cells, although epithelial cells were identified. The presence of pigmentation and a pagetoid growth pattern is consistent with a diagnosis of melanoma as opposed to P-SCC.
D. Metastatic breast carcinoma Lesions metastatic to the oral cavity are rare, accounting for less than 1 % of all oral malignancies. [ 7 ] When metastases occur in the oral cavity, over 90 % are localized to the bones of the mandible and maxilla, with less than 10 % affecting the soft tissues. [ 7 ] The most common primary sources of oral metastasis include the breasts, lungs, thyroid, kidneys, and prostate. [ 8 ] Metastasis to the oral cavity often is a sign of disseminated disease, but in some instances can be the initial metastasis or may signify an undiscovered primary malignancy. [ 7 ]
Clinically, oral metastases can mimic benign inflammatory or hyperplastic lesions, emphasizing the importance of maintaining a high index of suspicion, particularly in patients with a history of malignancies like breast cancer. [ 7 ] Late diagnosis is common due to their nonspecific presentation, contributing to the overall poor prognosis associated with metastatic oral lesions. [ 7 ]
Histologically, metastatic breast carcinoma may demonstrate features such as cellular atypia, comedonecrosis, and the formation of loosely cohesive multicellular or unicellular ducts reminiscent of breast tissue architecture. [ 7 ] These features can aid in distinguishing metastatic carcinoma from other oral malignancies. [ 7 ]
In this case, while there was a concern for metastasis, given the clinical history, the histopathological analysis did not support this diagnosis. The malignant cells demonstrated pigmentation and stained positive for melanocytic markers. Furthermore, no evidence of ductal structures or features characteristic of metastatic breast carcinoma were observed, ruling out metastasis from this glandular organ.
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