|Ahead of print publication
Basaloid squamous cell carcinoma in the maxillary gingiva
GB Protyusha, B Sivapathasundharam
Department of Oral Pathology and Microbiology, Faculty of Dentistry, Meenakshi Academy of Higher Education and Research, Meenakshi Ammal Dental College and Hospital, Chennai, Tamil Nadu, India
|Date of Submission||19-Oct-2019|
|Date of Decision||11-Feb-2020|
|Date of Acceptance||28-Apr-2020|
|Date of Web Publication||13-Oct-2020|
Department of Oral Pathology and Microbiology, Faculty of Dentistry, Meenakshi Academy of Higher Education and Research, Meenakshi Ammal Dental College and Hospital, Chennai, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Basaloid squamous cell carcinoma (BSCC) is a rare, unique, and aggressive variant of squamous cell carcinoma which mostly occurs in the upper aerodigestive tract. Histologically and immunologically different from conventional squamous cell carcinoma, it is mostly seen in men of the sixth and seventh decades and is commonly associated with tobacco and alcohol usage. BSCC usually presents as a high stage disease with distant metastasis, high recurrence rate, and poor prognosis. In the head-and-neck region, BSCC has a strong predilection for sites such as the base of the tongue, soft palate, and epiglottis. Less commonly, it may also occur on the floor of the mouth, gingiva, and tonsils. In the present article, we report a case of BSCC in the right maxillary anterior gingiva of a 57-year-old female for its rarity.
Keywords: Basaloid squamous cell carcinoma, comedonecrosis, maxillary gingiva, oral squamous cell carcinoma
| > Introduction|| |
Basaloid squamous cell carcinoma (BSCC), a rare variant of conventional squamous cell carcinoma (SCC) occurs in the upper aerodigestive tract and is composed of both basaloid and squamous components. This high-grade carcinoma may also occur in the oral cavity, especially in the posterior aspect typically near the base of the tongue, soft palate, epiglottis, and piriform sinus.,
Histologically, this tumor is characterized by the presence of variably sized solid epithelial nests composed of large basaloid cells showing comedo necrosis without transition to keratinisation, peripheral palisading, increased mitotic activity, and small cystic spaces filled with periodic acid-Schiff (PAS) positive hyaline-like material. This tumor is highly aggressive with an increased tendency for recurrences, distant metastasis, and poorer prognosis., This carcinoma should be differentiated from other malignant epithelial tumors of the oral cavity, namely, adenoid cystic carcinoma (ACC), adenosquamous carcinoma, basal cell adenocarcinoma, and small cell neuroendocrine carcinoma, as there are profound differences in their clinical nature, treatment, and prognosis., We report a case of BSCC in the gingiva of a 57-year-old female for its rarity.
| > Case Report|| |
A 57-year-old female reported with the complaint of a growth in the right upper front teeth region for the past 1 month, which showed a rapid rate of progression. On examination, a reddish irregular, nodular, and edematous mass in relation to the grossly decayed right upper anterior teeth and measuring about 7 cm × 6 cm [Figure 1] was present. On palpation, it was tender, soft, and bled. A provisional diagnosis of pyogenic granuloma was made, with carcinoma as the differential diagnosis. The lesion was excised.
|Figure 1: Photograph showing an erythematous irregular mass in the anterior gingiva|
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The biopsied specimen on gross examination was yellowish-grey and firm with a smooth cut surface.
Hematoxylin and Eosin stained section showed epithelial cells, infiltrating into the connective tissue [Figure 2]. The infiltrated cells were arranged in the form of follicles, islands, sheets, and strands [Figure 3]. This tumor was biphasic with central cuboidal and peripheral columnar cells. The columnar cells have granular nuclei and inconspicuous cytoplasm, exhibiting a palisading pattern. The central cells were small and cuboidal with dark, hyperchromatic granular nuclei and scanty cytoplasm, resembling basaloid cells [Figure 4] and [Figure 5]. Cystic degeneration and comedo type necrosis were evident in the tumor islands, with no evidence of keratinization [Figure 6]. Clear cells were also seen in few areas. These epithelial islands were separated by the thin hyalinized fibrous connective tissue.
|Figure 3: Infiltrated tumor cells arranged in the form of follicles, islands, sheets, or strands|
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|Figure 4: Tumor islands exhibiting a palisading pattern of peripheral tall and short columnar cells with granular nuclei and scanty cytoplasm, separated by the thin fibrous connective tissue|
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|Figure 5: Central basaloid cells showing dark hyperchromatic nuclei and inconspicuous cytoplasm|
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|Figure 6: The presence of comedo type necrosis in between the tumor islands|
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Immunohistochemistry was done for markers such as pan cytokeratin (CK), CK 18, CK 19, and smooth muscle actin (SMA). Tumor cells showed strong positivity for Pan CK [Figure 7] and negativity for CK 18, CK 19, and SMA.
|Figure 7: Immunohistochemical image of pan cytokeratin showing positivity for the tumor cells|
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Correlating the clinical, histopathological and immunohistochemical (IHC) findings, a definitive diagnosis of BSCC was made.
| > Discussion|| |
BSCC is a rare, aggressive malignancy. The WHO (2017) defined BSCC as a clinically unfavorable variant of SCC composed of a prominent basaloid component and squamous cell differentiation.
BSCC presents with distinct morphologic and histologic features. It primarily occurs in the upper aerodigestive tract. The occurrence of this tumor in the oral cavity is relatively uncommon.
Till date, about fifty cases reported in the oral cavity showed a strong predilection for the base of the tongue (61%), followed by the floor of the mouth (30%). BSCC involving gingiva is extremely rare and to the best of our knowledge, only 11 cases have been recorded so far. The present case involved the maxillary gingiva, which is an unusual site.
Commonly associated with tobacco and alcohol usage, this tumor is usually seen among men in the sixth and seventh decades. The present case, however, was seen in a female with no history of deleterious habits.
Other etiological causes include smokeless tobacco and exogenous factors, namely environmental, nutritional, or occupational. Recently, human papillomavirus and herpes simplex virus are also implicated as etiological factors. The possible etiology in the present case could be attributed to the potential role of these viruses as the patient denied any history of tobacco/alcohol usage.
Theories proposed regarding the origin of BSCC include totipotent cells of the basal layer of the epithelium or from the minor salivary gland ducts of the larynx, hypopharynx, and tongue. It was also suggested that the “basaloid” pattern found anywhere within the body is actually an attempt at glandular differentiation., However, this is unlikely, since oral lesions also occur in the gingiva, a site devoid of glands.
Clinical presentation of this aggressive tumor is similar to that of conventional SCC.,
The present case clinically mimicked a relatively harmless pyogenic granuloma due to its soft, vascular nature, and location; however, a differential diagnosis of carcinoma was given considering its rapid growth rate.
Despite having distinct histological features, BSCC is often difficult to distinguish from few other oral epithelial malignancies due to their overlapping features, which include a solid variant of ACC, adenosquamous carcinoma, SCC, basal cell adenocarcinoma, and peripheral ameloblastoma. Other rare tumors that may mimic BSCC are salivary duct carcinoma, small cell neuroendocrine carcinoma, and basal cell carcinoma.
Solid variant of ACC, also has a basaloid appearance consisting of sheets/islands of tumor cells with an angulated hyperchromatic nucleus and scanty cytoplasm. However, the absence of squamous differentiation, the presence of myoepithelial cells, and perineural invasion distinguish it from BSCC., Positive immunostaining of ACC with SMA and its absence in BSCC further helps in its differentiation.
None of the tumor cells showed SMA positivity in the present case, further confirming our histopathological diagnosis.
Adenosquamous carcinoma shows glandular structures lined by basaloid, columnar, or mucin-secreting cells where intracytoplasmic mucin stains positive for mucicarmine staining. Mucin positivity with true acinar-ductal differentiation in adenosquamous carcinoma helps to distinguish it from BSCC.
Although OSCC and BSCC are clinically similar, OSCC shows an absence of stromal hyalinization and cystic spaces filled with PAS-positive material that is present in BSCC, and hence it can be differentiated.
Similar to BSCC, Basal cell adenocarcinoma is also composed of basaloid cells with two-cell morphology. However, the absence of squamous differentiation and focal necrosis in basal cell adenocarcinoma helps in differentiating the two.
Basal cell ameloblastoma can be distinguished from BSCC by the presence of odontogenic epithelium and the absence of central comedo necrosis or any squamous component. Finally, basal cell carcinoma, though histologically similar to BSCC, is extremely rare in the oral cavity.
BSCC is much worse in its clinical behavior as compared to conventional SCC. A series of five cases reported by Altavilla et al. suggested that BSCC affecting the oral cavity and the oropharynx shows an aggressive behavior with cervical lymph node metastasis, perineural invasion, and distant metastasis to the lungs, liver, brain, skin, and bone, exhibiting a poor prognosis.
Although there is no specific IHC diagnostic pattern for this tumor, the use of CKs 1, 7, 14, epithelial membrane antigen, Cam 5.2, pankeratin AE/AE3, and squamous epithelial marker 34 βE12 were reported to be useful markers for this tumor.
The present case showed positive immunostaining for pan CK establishing the epithelial origin. SMA staining ruled out salivary gland origin, while negative staining for CK 18 and CK 19 eliminated the possibility of an odontogenic origin. The histologic features of our case coinciding with that of BSCC, supported by the IHC findings led us to the definitive diagnosis of BSCC.
The aggressive nature of this tumor accounts for its poor prognosis with an overall 3-year survival rate of only 28.5%.
BSCC, being a unique, histologically varied, and highly aggressive variant of SCC, often pose a challenge for its diagnosis and should, therefore, be done with caution.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]