Submandibular Gland Adenoid Cystic Carcinoma Presenting as Intracranial Metastasis
Year: 2024
Type: article
Study design: Case Report
Abstract: Sir, A 59-year-old woman presented with a recent onset of frontal swelling four years later, to the primary asymptomatic lesion in the submandibular gland. She also had a mild on-and-off headache over the last few weeks. A plain and contrast-enhanced computed tomography (CT) scan of the head revealed a well-defined, hypervascular extra-axial mass centered at the midline high frontal region of the scalp. The mass measured 44 × 42 × 48 mm and caused a sunburst periosteal reaction of the underlying medial aspects of both frontal bones. The lesion was straddling both sides of the frontal bones, along with infiltration into the parafalcine region of bilateral frontal lobes [Figure 1a and b]. The diagnostic possibilities offered on a CT scan were metastasis, hemangiopericytoma, and aggressive meningioma. A firm-to-hard swelling was also palpated in the left submandibular region, measuring 4.5 × 2.5 × 2.0 cm. On ultrasonography, it was heterogeneous and hypoechogenic with well-defined margins. An ultrasound-guided fine-needle aspiration (FNA) was done from both the submandibular and frontal swellings. The FNA cytology smears revealed multi-layered clusters with papillaroid fragments of small, monotonous, uniform basaloid-type malignant epithelial cells with round to oval hyperchromatic nuclei, indistinct nucleoli, and scant cytoplasm. Occasional extracellular hyaline globules were also noted [Figure 2a–d]. Cell blocks were also prepared from both the frontal and submandibular swellings. The sections from the cell blocks showed a tumor disposed in a cribriform pattern, displaying hyperchromatic angulated nuclei and a scant amount of cytoplasm [Figure 3a and b]. The tumor showed strong and diffuse cytoplasmic expression for anti-c-kit antibodies in the epithelial component of the tumor and anti-p63 antibody positivity in the myoepithelial component. A final diagnosis of submandibular adenoid cystic carcinoma (ADCC) with metastasis to the frontal lobes was rendered. Following the cytological diagnosis, the patient underwent a PET-CT scan. A PET-CT scan of the brain revealed an FDG-enhancing soft tissue density mass measuring 4.6 × 4.5 × 4.0 cm in the midline frontal region of the scalp. This mass destroyed both frontal bones. The mass caused compression on the bilateral frontal lobes of the brain parenchyma with superficial infiltration. A heterogeneously enhanced soft tissue density mass lesion measuring 3.3 × 3.2 × 2.5 cm was also noted in the left submandibular gland. The fat plane appeared intact, with adjacent structures. A PET-CT scan of the thorax showed enlarged mediastinal lymph nodes in the superior mediastinum, upper paratracheal and lower paratracheal structures, and multiple lung nodules. The skeletal system also showed a few lesions in the right ala of the sacrum and bilateral iliac bones. The patient has been scheduled for subsequent surgery and platinum-based chemoradiotherapy.Figure 1: (a and b) A CT scan shows that there is an extra-axial mass in the frontal region. This mass is destroying the frontal bones underneath in a pattern that looks like a sunburst. The lesion was infiltrating the parafalcine region of the bilateral frontal lobes (black arrows)Figure 2: (a) Fine-needle aspiration cytology smear from the left submandibular gland showing a cellular smear comprising of multi-layered clusters and papillaroid fragments on a hemorrhagic background with pink eosinophilic material (x40, MGG stain). (b) Cytology smear from left submandibular gland showing a monotonous population of small hyperchromatic tumor cells displaying nuclear crowding, molding, and a few hyaline globules marked with a red arrow (x200, MGG stain). (c) High-power view of a cytology smear from the frontal swelling showing papillaroid fragments of tumor cells with hyaline globules marked with a red arrow (x400, MGG stain). (d) A cytology smear from the frontal lobe displays tumor cells disposed in a cribriform pattern and tubules on a background of eosinophilic material admixed with blood having hyperchromatic angulated nuclei (x400, MGG stain)Figure 3: (a) Section from a cell block prepared from the frontal lobe showing a tumor disposed in a cribriform pattern entrapped in eosinophilic material admixed with blood (x40, H and E stain); (b) High-power view displaying individual tumor cells having hyperchromatic angulated nuclei and a scant amount of cytoplasm (x400, H and E stain). Tumor cells show immunoreactivity for antibodies to c-kit (CD117) (inset)The estimated incidence of adenoid cystic carcinoma is 3–4.5 cases per million per year, accounting for 10%–12% of all salivary gland tumors. The main characteristic feature of ADCC is perineural spread and multiple local recurrences.[1] The tumor can reach the intracranial space either directly through the skull base or by perineural invasion. Although hematogenous spread to the lung, liver, and bone is common in the late stages of disease, hematogenous metastases to the CNS are quite rare.[2] Very few cases of intracranial metastatic ADCC have been reported in the literature, mimicking hemangiopericytoma or aggressive meningioma on radiology.[3] Metastatic ADCC can cause significant peritumoral edema and contrast enhancement; hence, distinguishing this tumor from other intracranial lesions is difficult on radiology.[4] To date, very few cases of adenoid cystic carcinoma with intracranial metastasis have been reported [Table 1]. Intracranial metastasis of adenoid cystic carcinoma of the submandibular gland is an extremely rare entity, and the treatment for such lesions must be tailored according to the case. Treatment of intracranial metastatic ADCC often involves surgical resection and postoperative radiotherapy. Whenever better options other than surgical resection, such as stereotactic or whole-brain radiotherapy, are available, they should be considered. Chemotherapy options for ADCC are very limited; however, cisplatin-based chemotherapy has shown a response in a few cases.[4] There must be an evaluation of targeted therapies like anti-FGF, EGFR, and tyrosine kinase inhibitors in recurrent and advanced ADCC, as to date these therapies have not been proven to have long-term efficacy.[5]Table 1: Cases of salivary ADCC with intracranial metastasisThe overall prognosis of metastatic ADCC is very poor because of limited chemotherapy options and the propensity for late recurrence at local and distant sites. Thus, a meticulous clinical, radiological, cytological, and immunohistochemical correlation is required in the management of this rare entity. This case re-emphasizes the role of a simple and minimally invasive test in diagnosing a rare, catastrophic lesion. 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. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.
Source: Neurology India
Language: English
Subfield: Surgery
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
OpenAlex ID: W4392613409