Collagenous crystalloids in myoepithelial carcinoma: report of a case and review of the literature

Rare Floret Like Tyrosine Crystals in Pleomorphic Adenomas of Parotid Gland

The pleomorphic adenoma arising in the parotid gland is a benign neoplasm that is aptly named because of its histomorphological diversity. The stromal component can contain chondromyxoid material, amyloid, and elastic fibers, along with a few rare reports of crystalline structures present in this tumor. Especially, the crystalline components are rarely encountered or appreciated in routine pathology reporting. Here, we report a case of pleomorphic adenoma of the parotid gland, in which tyrosine-rich crystalloids were identified in abundance and were confirmed with special stains and electron microscopy. Though their exact source is not yet known, crystallization of the stromal or myoepithelial cell secretion has been hypothesized. This comprehensive report is to make the histopathologists aware of this rare morphological observation in pleomorphic adenomas so that more cases are identified and followed-up to reveal the impact of their presence in a subset of pleomorphic adenomas.

Crystals and crystalloids in cytopathology: Incidence and importance

Many crystals and crystal-like structures may be encountered in cytopathology practice and can represent both beautiful novelties and diagnostic aids. The authors present an organ-specific review of the published literature on crystals combined with personal experiences. The purpose is not only to serve as a reference guide by highlighting the clinical and morphologic features of crystals, crystalloids, and crystal-like structures but also to review their significance and to offer reporting strategies in cases that bear management implications.

Myoepithelial Carcinoma Arising in a Plasmacytoid Myoepithelioma of the Parotid Gland Synchronized with Melanoma: A Case Report and Review of the Literature

Myoepithelial carcinoma, also known as malignant myoepithelioma, is considered an extremely rare (0.45-1%) malignant salivary gland neoplasm. Approximately 100 cases have been reported in the English-language literature on myoepithelial carcinoma. The majority of the myoepitheliomas described in the literature have been benign, and the malignant counterpart is considered rare (<1%). Such a tumor may appear de novo or rarely develop from a preexisting pleomorphic adenoma (<20%), and in exceedingly rare cases (<0.5%), it has arisen from a benign myoepithelioma (i.e., plasmacytoid myoepithelioma). To our knowledge, no case of myoepithelial carcinoma of the parotid gland arising in a plasmacytoid myoepithelioma synchronized with melanoma has been reported to date. The treatment of myoepithelial carcinoma has been mainly surgical, including wide excision with free margins, with or without nodal dissection. The roles of chemotherapy and radiotherapy have not yet been established. We report a case of myoepithelial carcinoma of the parotid gland arising in a plasmacytoid myoepithelioma synchronized with melanoma in a 40-year-old woman. In our case, a complete response was achieved with surgery followed by adjuvant chemotherapy based on carboplatin and paclitaxel concurrent with radiotherapy.

Crystalloids in FNA specimens of salivary gland lesions: A retrospective study in a single large institute

BACKGROUND

Identifying crystalloids, which includes amylase and tyrosine crystalloids, is relatively uncommon in salivary gland fine-needle aspiration (FNA) cytology. Although it has been suggested that the presence of crystalloids favors a benign process, the full significance has not been well established.

METHODS

The authors performed a review of slides from all salivary gland FNA cases received in their laboratory from January 2017 to September 2019 to identify cases with crystalloids (screened cohort). In addition, the departmental archives were searched retrospectively for all salivary gland FNA cases that had specifically reported crystalloids. Cytologic findings as well as correlation with surgical pathology and clinical follow-up were examined.

RESULTS

There were 664 cases in the screened cohort. Crystalloids were present in 37 cases (incidence, 5.6%). Amylase crystalloids were the most commonly identified (n = 28; 75%), followed by tyrosine crystalloids (n = 4; 11%), and collagenous crystalloids (n = 1; 3%). Four cases with crystalloids could not be further classified because of low quantity (n = 4; 11%). An additional 54 cases were identified in the 10-year retrospective review. Diagnostic categorization for the total cohort (N = 91) was as follows: nondiagnostic, 30 cases (33%); nonneoplastic/benign, 42 cases (46%); neoplasm: benign, 10 cases (11%); and atypia of undetermined significance, 9 cases (10%). Twenty-six cases had subsequent resection findings, including oncocytic cyst/cystadenoma in 8 cases (31%), chronic sialadenitis/ductal obstructive change in 7 cases (27%), pleomorphic adenoma in 5 cases (27%), developmental cyst in 3 cases (12%), lymphoepithelial cyst in 2 cases (8%), and Warthin tumor in 1 case (4%).

CONCLUSIONS

This cohort represents the largest FNA series of salivary gland crystalloids. All cases were associated with nonneoplastic or benign neoplastic lesions.

Crystalloid Granuloma of Parotid Gland: A Case Report With Review of the Literature

Crystalloid granuloma (CG) of salivary gland is an extremely rare inflammatory disease, and only 6 cases have been reported in the English literature. CG is histologically characterized by a granulomatous reaction to amylase crystalloid deposition. A 73-year-old woman presented with a painful left neck mass. Computed tomography depicted a mass located in the lower pole of the left parotid gland, suspicious for a tumoral lesion. Preoperative fine needle aspiration cytology found amylase crystalloid deposition with a few inflammatory cells. Surgical sections of the mass revealed formation of a granuloma containing abundant eosinophilic but glassy and transparent amorphous crystalloids, suggestive of α-amylase crystalloid. No neoplastic elements were detected. The case was eventually diagnosed with CG in the parotid gland. Our findings suggest that when we identify amylase crystalloids in fine needle aspiration cytology smears from the salivary gland, CG should be considered even if neoplasm is clinically or radiographically suspected.

Meningioma With Tyrosine-Rich Crystalloids: A Case Report and Review of the Literature

We report a case of fibrous meningioma with tyrosine-rich crystalloid in the frontal lobe of a middle-aged woman. The patient presented with a history of several years of worsening headaches and blurry vision, which progressed to include syncopal episodes and right-sided weakness. Imaging demonstrated a dural-based extra-axial mass arising from the right orbital roof and extending superiorly along the right frontal convexity causing right-to-left midline shift. The patient underwent a craniotomy and operative resection. Tumor architecture and cytology was similar to that of a Schwannian neoplasm, with spindled cells arranged in a fascicular architecture and displaying focal nuclear palisading. Immunohistochemical stains confirmed a diagnosis of fibrous meningioma. Light microscopy demonstrated extracellular deposits of eosinophilic crystalline material parallel to the spindled tumor cells, reminiscent of "tyrosine-rich" crystals described in salivary gland neoplasms. This is the third meningioma featuring tyrosine-rich crystalloid reported in the literature; we also summarize the previous 2 reports.

Crystalloids in submandibular sialadenitis

Fine needle aspiration cytology of the salivary glands plays an important role in the diagnosis of neoplastic and non neoplastic lesions of salivary gland. Crystalloids in salivary gland lesions are a rare occurrence. A case of submandibular sialomegaly in an elderly patient with a clinical suspicion of metastasis was subjected to FNAC which showed crystalloids morphologically resembling amylase occurring in a background of sialadenitis. These crystals are non birefrigent, eosinophilic structures with a variety of geometric shapes including needles, rods, rectangular structures that do not stain with mucin stains. Other important crystalloids which can be observed in neoplastic and non-neoplastic salivary gland lesions are tyrosine-rich crystalloids, collagenous crystalloids, and oxalate crystals. These can be distinguished both morphologically and on the basis of several staining techniques in addition to biochemical studies. FNAC plays a major role in the diagnosis of these lesions and helps in avoiding unnecessary surgery.

Crystalloid granulomas of the parotid gland mimicking tumor: a case report with review of the literature

Crystals and crystalloids may be seen in salivary glands in association with tumors and cysts. Rarely, crystalloids may lead to granulomatous reaction mimicking neoplasm and infectious diseases. We present the case of an 81-year-old man with right parotid gland swelling and a clinical and radiological diagnosis of tumor. A granulomatous inflammation was seen on intraoperative pathology. On final pathology, the parotid gland showed multiple granulomas with central cavitation and palisading histiocytes with eosinophilic intracytoplasmic and extracellular crystalloids. The crystalloids were variably shaped, needle-like, polyhedral, rhomboid, rectangular and irregular, nonpolarizable, nonbirefringent, and nonrefractile and were orange-red with trichrome and bluish-purple with Brown and Brenn stain. Remnants of a duct lining within the lesion suggested a granulomatous response to ruptured cyst contents releasing secretions supersaturated in proteins and their precipitates.

α-amylase crystalloid granuloma of the parotid gland: case report and review of the literature

We report a case of α-amylase crystalloid granuloma of the parotid gland in a 65-year-old Japanese woman. Histopathologically, the lesion comprised cystlike dilatation of the ducts and foreign body granulomas, with deposits of numerous crystalloid structures. The crystalloids were eosinophilic and varied in size and shape. Immunohistochemically, the crystalloids were positive for α-amylase. Immunoelectron microscopy showed the crystalloids to be cuboidal or rectangular in shape with irregularly shaped central spaces. We discuss this rare condition and review the literature on α-amylase crystalloids.

Common Malignant Salivary Gland Epithelial Tumors

Malignant salivary gland epithelial tumors are histologically diverse with at least 24 recognized distinct entities. In general, malignant tumors account for 15% to 30% of parotid tumors, 40% to 45% of submandibular tumors, 70% to 90% of sublingual tumors, and 50% of minor salivary tumors. Common malignancies include mucoepidermoid carcinoma, adenoid cystic carcinoma, acinic cell carcinoma, salivary duct carcinoma, carcinoma ex pleomorphic adenoma, polymorphous lowgrade adenocarcinoma, and myoepithelial carcinoma. Each tumor type has its own unique histologic variants and prognostic pathologic features, and only mucoepidermoid carcinomas have a formalized grading system. The molecular pathogenesis of certain tumors, such as mucoepidermoid carcinoma and adenoid cystic carcinoma, has recently begun to be elucidated.

Rare Malignant and Benign Salivary Gland Epithelial Tumors

Although at least 24 distinct histologic salivary gland carcinomas exist, many of them are rare, comprising only 1% to 2% of all salivary gland tumors. These include epithelial-myoepithelial carcinoma, (hyalinizing) clear cell carcinoma, basal cell adenocarcinoma, cystadenocarcinoma, low-grade salivary duct carcinoma (low-grade cribriform cystadenocarcinoma), oncocytic carcinoma, and adenocarcinoma not otherwise specified. Few tumors (clear cell carcinoma and basal cell adenocarcinoma) have unique molecular correlates. Benign tumors, although histologically less diverse, are far more common, with pleomorphic adenoma and Warthin tumor the most common salivary gland tumors. Many benign tumors have malignant counterparts for which histologic distinction can pose diagnostic challenge.

Salivary oncocytic cystadenoma with intraluminal crystalloids: a case report with review of the literature

Oncocytic cystadenoma is a rare benign tumor of major salivary glands that in rare occasions may present histologically with intraluminal crystalloids. We report a case of 53-year-old man with a progressively enlarging lump in the left submandibular region. Ultrasound examination revealed a cystic mass with an intraluminal fluid collection. The tumor was surgically removed. Histologic examination yielded a diagnosis of oncocytic cystadenoma with a high concentration of intraluminal crystalloids. The microscopic features of the crystalloids were compatible with nontyrosine (alpha-amylase) crystalloids. When compared with previously published cases in the literature, this is the first report of oncocytic cystadenoma with intraluminal crystalloids arising in the submandibular gland, and the second reported case of the nontyrosine type of crystalloids occurring in association with this tumor. The nontyrosine crystalloids may be highly characteristic to salivary gland tumors with oncocytic differentiation.

Intrafollicular collagenous crystalloids in a hair follicle of the nose

The authors report an unusual case of intrafollicular collagenous crystalloids in an 86-year-old woman. The presence of collagenous crystalloids within the follicular epithelium is intriguing and has not been described previously.