Acinic cell carcinoma arising in a parotid lymph node

Heterotopic acinic cell carcinoma and its clinical implications

This is a review of the clinical and histopathological published data on very rare heterotopic acinic cell carcinomas (AcCCs) with suggested optimal management. Extrasalivary AcCCs originate primarily in parotid lymph nodes. They present at low clinical stage, show mostly low-grade histopathology and are circumscribed with a complete nodal capsule. Extracapsular dissection was advocated as adequate therapy. In rare cases with positive surgical margins, a completion parotidectomy or adjuvant radiotherapy should follow. Heterotopic high-grade AcCCs are rare, necessitating radical surgery including neck dissection and adjuvant radiotherapy. The short term prognosis is excellent, long term outcomes are not known. Longer term follow-up is essential.

Salivary Intraductal Carcinoma Arising within Intraparotid Lymph Node: A Report of 4 Cases with Identification of a Novel STRN-ALK Fusion

Intraductal carcinoma (IDC) is a rare salivary gland tumor that is considered analogous to ductal carcinoma in-situ of the breast, demonstrating a complex neoplastic epithelial proliferation surrounded by a continuous layer of presumed non-neoplastic myoepithelial cells. It is subcategorized into intercalated duct, apocrine, and hybrid subtypes based on morphologic and immunohistochemical features, with frequent NCOA4-RET and TRIM27-RET fusions, respectively, seen in intercalated duct and hybrid tumors. However, as an expanding clinicopathologic spectrum of IDC has been documented, controversy has emerged as to whether this tumor type is best defined by its intraductal growth pattern or distinctive molecular and immunophenotypic differentiation. Here, we further explore the nature of IDC by evaluating four cases that arose within intraparotid lymph nodes. These intercalated-duct phenotype tumors with diffuse S100 protein expression demonstrated a crowded and complex epithelial proliferation arranged in cystic, cribriform, and micropapillary architecture, surrounded by an intact myoepithelial cell layer, and were completely intranodal. Of two tumors with tissue available for molecular analysis, one demonstrated a NCOA4-RET fusion and one harbored a STRN-ALK fusion that is novel to IDC. Not only does the intranodal presence of IDC present a challenging differential diagnosis, but the complex nature of this proliferation within lymph node tissue raises questions as to whether the myoepithelial component of IDC is actually non-neoplastic in nature. Furthermore, identification of a STRN-ALK fusion expands the genetic spectrum of IDC and adds to evidence of an emerging role for ALK in salivary gland tumors. Further attention to the nature of the myoepithelial cells and documentation of alternate fusion events in IDC may inform continued discussion about its appropriate classification.

Synchronous Parotid (Mammary Analog) Secretory Carcinoma and Acinic Cell Carcinoma: Report of a Case

Mammary analogue secretory carcinoma (MASC) is a recently described low-grade salivary gland malignancy with histologic, immunohistochemical and molecular similarities to secretory carcinoma of the breast, including a specific t(12;15)(p13;q25) resulting in an ETV6-NTRK3 gene fusion. Ultrasound and magnetic resonance imaging frequently document a macrocystic structure. The main differential diagnosis of secretory carcinoma is with low grade acinic cell carcinoma (AciCC). The two can be differentiated with immunohistochemical stains for S100, mammaglobin, carbonic anhydrase VI and DOG-1; the identification of the specific translocation can help to characterize non-typical cases. We report a unique case of synchronous MASC and AciCC presenting in a parotid gland and discuss the implications of the correct identification of the two tumors.

Two Unusual Cases of Acinic Cell Carcinoma: Role of Cytology with Histological Corelation

Acinic Cell Carcinoma (AcCC) is a slow growing, malignant tumour of salivary glands, predominantly found in parotid gland and rarely in submandibular gland or minor salivary glands. Rarely, the tumour can arise in Heterotopic Salivary Gland Tissue (HSGT) and can present bilaterally. Synchronous contralateral tumour or tumour arising in HSGT is easily missed clinically. Fine Needle Aspiration Cytology (FNAC) is an important preoperative diagnostic investigation in cases of AcCC. Sometimes its diagnosis on cytology is very difficult and it is easily misdiagnosed as benign, affecting the long term prognosis. Here, we present two unusual cases of AcCC. One developed in HSGT and the other was synchronous bilateral. Though the histological features of AcCC appear to be characteristic but clinical suspicion and cytological features have been described as equally important for preoperative diagnosis. Present cases highlight the importance of a cytopathologist who plays an important role in its preliminary diagnosis.

Lymphoepithelial carcinoma of the parotid gland arising in an intraglandular lymph node: report of a rare case mimicking metastasis

We present a case (female patient aged 40 years) with a primary Epstein-Barr virus-associated lymphoepithelial carcinoma of the parotid gland that was confined to an intraparotid lymph node. This appearance of the tumor simulated a metastasis that was excluded by exhaustive radiologic and clinicopathologic investigations.

Unexpected findings in neck dissection for squamous cell carcinoma: Incidence and implications

BACKGROUND

During the pathologic examination of neck dissections, unexpected pathologic findings may occasionally be encountered. These pathologic findings may simulate malignant disease and/or have implications on the already complicated management of patients with head and neck cancer.

METHODS

We retrospectively reviewed 202 consecutive patients with a preoperative diagnosis of squamous cell carcinoma (SCC), who underwent 307 neck dissections performed by a single surgeon and examined by a single pathologist.

RESULTS

Ten patients had an unexpected finding. These included metastatic papillary thyroid carcinoma, leukemia, lymphoma, Warthin's tumor, and tuberculosis. Two of three patients with benign-appearing thyroid tissue within lymph nodes received no further treatment, and both remained well beyond 6 years. Four patients succumbed to SCC; none died from the incidentally discovered pathologic findings.

CONCLUSIONS

Unexpected pathologic findings may be present in more than 3% of neck dissections. Although this is usually indolent, with the underlying SCC remaining the main prognostic determinate, it may significantly complicate postoperative management.

Primary acinic cell carcinoma of the lung with lymph node metastasis

We report the case of a 30-year-old woman who presented with a subpleural mass in the lower lobe of the right lung, which was found incidentally on a routine chest radiograph. A wedge biopsy followed by lobectomy and lymph node staging revealed an acinic cell carcinoma with involvement of a hilar lymph node. The subcarinal and mediastinal lymph nodes were free of tumor. Perineural invasion was identified at the periphery of the tumor. There was no evidence of origin from salivary gland or involvement of any other organ. The patient was well 12 months postoperatively. To our knowledge, this is the second case report featuring lymph node metastasis in an acinic cell carcinoma of the lung and the first to demonstrate perineural invasion.

Lymphadenoma: a report of three cases of an uncommon salivary gland neoplasm

AIMS

Lymphadenoma of the salivary gland is a rare neoplasm that has not been properly characterized. This study describes the clinicopathological features of three cases.

METHODS AND RESULTS

All three patients were males, ranging in age from 13 to 57 years. Two presented with a parotid mass, and one a preauricular mass. The tumours were well circumscribed, comprising anastomosing trabeculae, solid tubules, glands or basaloid islands of epithelium with or without cyst formation, accompanied by a prominent lymphoid stroma lacking sinuses. Large reactive lymphoid follicles were found in two cases. The epithelial cells were bland-looking to mildly atypical. Immunostaining demonstrated dual luminal cell and abluminal basal cell differentiation, with the former being often subtle and highlighted only by immunostaining for epithelium membrane antigen or CAM 5.2, and the latter being highlighted by p63 immunostain.

CONCLUSIONS

Although there is some variation in the histological pattern from case to case, lymphadenoma is a morphologically recognizable salivary gland adenoma characterized by a dense lymphoid infiltrate. Lack of familiarity with this tumour may lead to misdiagnosis as myoepithelial sialadenitis, lymphoma, metastatic carcinoma in lymph node or lymphoepithelial carcinoma.

Well-differentiated acinic cell carcinoma of salivary glands associated with lymphoid stroma

In a multicenter study, 69 acinic cell carcinomas of the salivary glands were identified, of which 12 constituted what the authors believe to be a distinct subgroup. Their most noticeable feature was a dense lymphoid stroma with well-developed germinal centers, surrounding a sometimes scanty epithelial component, which in each case had a microcystic growth pattern. All these tumors were enveloped by a thin fibrous pseudocapsule, thus mimicking an intraparotid lymph node containing a metastasis. All 12 cases showed low MIB1 proliferative activity, with a mean index of 1.7% (range, 0.5 to 3.7). All patients remained well without recurrence or metastasis in followup periods of 19 months to 14 years. A second subgroup of nine acinic cell carcinomas also possessed a heavy lymphoid stroma with germinal centers, but its distribution was more patchy than in the first subgroup, and in addition, the fibrous pseudo-capsule was incomplete or absent. In each case the epithelial growth pattern was other than microcystic. These tumors had significantly higher MIB1 indices (mean, 17%; range, 3.4 to 45). In contrast to the first subgroup, only three of nine patients remained well with no further disease. The other six patients developed recurrences or metastases, and two died of disseminated cancer. In view of the clinical and pathological data, it is speculated that the tumor foci lacking lymphoid stroma in each of the second subgroup possibly represented a clone of high-grade malignancy arising within a low-grade acinic cell carcinoma with lymphoid stroma.