Dual Cell Population Research Articles

“Synchronous Development of Acute Myeloid Leukemia and Multiple Myeloma: A Rare Case Presentation”

Abstract Introduction/Objective The co-occurrence of acute myeloid leukemia (AML) and multiple myeloma (MM) presents a diagnostic challenge, particularly when it arises without prior chemotherapy exposure. This study aims to elucidate the clinical characteristics, diagnostic approach, and management implications of such synchronous hematologic malignancies through a detailed case report. Methods/Case Report A 64-year-old female with no previous medical history presented with chest pain, shortness of breath, and hematologic abnormalities. Clinical evaluation revealed severe pancytopenia, cystic liver mass, enlarged retroperitoneal lymph nodes, and hypercalcemia. Peripheral blood smear indicated hematologic malignancy, prompting further investigation. Bone marrow aspirate analysis, including flow cytometry and immunohistochemical stains, was performed to confirm the dual cell populations of AML blasts and MM plasma cells. Results (if a Case Study enter NA) Flow cytometric analysis and immunohistochemical stains of the bone marrow aspirate confirmed the presence of distinct cell populations: blasts expressing markers consistent with AML and abundant plasma cells indicative of MM. Monotypism of plasma cells was established, with kappa predominance. Notably, there was no coexpression of markers between the AML blasts and MM plasma cells. Conclusion This case highlights the rare occurrence of synchronous AML and MM in a patient without prior chemotherapy exposure. The diagnostic approach involving flow cytometry and immunohistochemical stains proved essential in confirming the dual hematologic malignancies. Clinicians should be vigilant for such presentations, as timely diagnosis and appropriate management are crucial for optimizing patient outcomes in these complex cases.

Abstract 5930: Measuring apoptotic effects of EP4A1 and EP4A2 on Kuramochi with a high-throughput multiplex image cytometric method

Abstract Ovarian cancer accounts for approximately 6% of all cancer death in women and has one of the highest mortality rates out of all gynecologic malignancies in the United States. Ovarian cancer can exhibit innate or acquired chemoresistance behavior, thus it is critical to identify novel therapeutic drug candidates. One of important characteristics of identifying potential chemotherapy drug candidate is the ability to induce apoptosis or programmed cell death in the target cancer cells. In order to measure apoptosis, various biomarkers are commonly employed such as Caspase 3, 7, 8 or 9, as well as Annexin V, which are all part of the cascade in apoptotic intrinsic pathway. However, typical fluorescent staining for image cytometry is not multiplexed that required multiple steps in order to determine the different type of apoptotic populations. In this work, we demonstrate a multiplexing apoptosis detection method to investigate the apoptotic effects of EP4A1, EP4A2, Paclitaxel, and Carboplatin on Kuramochi ovarian cancer cells. We employed the use of a high-throughput plate-based image cytometer (Celigo, Revvity Health Sciences Inc.) to image and analyze drug-treated Kuramochi cells stained with Annexin V-APC, Caspase 3/7 (488), and propidium iodide (PI) to assess the early- and late-stage apoptosis, as well as necrosis. We expected to see an increase in dual staining with the addition of EP4A to paclitaxel and carboplatin; however, the more interesting data was observed by separating single positive cell populations (Caspase, Annexin or PI only) from dual positive cell populations (Annexin + PI, Caspase + PI, Annexin +PI). The results show that treatment with EP4A lead to a time dependent increase in Caspase 3 cleavage but only in the single positive cell population. This trend was also observed in Annexin V single positive cell populations which is an indication of early apoptosis. The additive effect observed with the addition of EP4A was not seen in the dual positive cell populations. The high throughput nature of the image cytometry also allowed us to easily and quickly determine the optimal treatment conditions for this experiment. We were able to record multiple time points and not only capture proliferation, but also simultaneously collect data on caspase cleavage, Annexin-V staining and PI staining on multiple concentrations of compounds in monotherapy, dual therapy, and triple therapy combinations. Typically, it may be difficult to test multiple conditions in duplicate and triplicate using flow cytometry, while Celigo Image Cytometry may be used to obtain more robust data, and simultaneously acquire data of proliferation and multiplex staining with Annexin-V, PI and Caspase 3/7. Citation Format: James McDonald, Leo Li-Ying Chan, Jocelyn Reader, Sergio Mojica, Mackenzie Pierce. Measuring apoptotic effects of EP4A1 and EP4A2 on Kuramochi with a high-throughput multiplex image cytometric method [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5930.

Metastatic Hidradenocarcinoma of Inguinal Region: A Cytological Diagnosis

Abstract Hidradenocarcinoma is an unusual malignant tumor of the sweat gland with a high local recurrence and lymph node metastasis. They are primarily located in the head and neck, and trunk. Here, we present a case of hidradenocarcinoma recurrence with metastasis to the right inguinal region, which is a rare occurrence. In cytology, dual population of cells, consisting of eosinophilic and clear cells, can be observed, which are arranged in clusters, tubules, and papillae showing pleomorphism, along with extracellular hyaline material and necrosis. Although excision biopsy is needed for diagnosis, fine needle aspiration can be a simple and minimally invasive method in preoperative diagnosis.

Mixed epithelial and stromal tumor of the seminal vesicle: A case report and literature review

A mixed epithelial and stromal tumor of the seminal vesicle gland is an uncommon neoplasm characterized by a dual population of epithelial and stromal cells. In this case report, we present a 59-year-old male patient who presented with a large, 10 cm mass in the left seminal vesicle, which was preliminarily suspected to be a malignant tumor of the seminal vesicle based on magnetic resonance imaging findings. Histopathological evaluation, however, revealed a tumor with biphasic epithelial–mesenchymal differentiation, predominantly displaying mesenchymal characteristics. The epithelium and stroma displayed papillary and foliar structures, respectively. The epithelial cells were bland, arranged in either single or multi-layered cuboidal patterns, and the stromal cells were spindle shaped with a sparse distribution. The patient experienced a favorable postoperative outcome. The diagnosis of mixed epithelial and stromal tumor is challenging based on clinical and imaging findings alone, and definitive diagnosis relies on pathological examination. This case report addresses a rare presentation of low-grade mixed epithelial and stromal tumor in the seminal vesicle gland and aims to expand the understanding of this entity by reviewing the relevant literature.

Bronchial cytology of pulmonary adenoid cystic carcinoma – A multi-institute series with emphasis on immunocytochemistry

BackgroundPulmonary adenoid cystic carcinoma (AdCC) is a central and superficial primary lung neoplasm, well-suited for sampling by bronchial cytology. This study aims to review the cytologic features of pulmonary AdCC on bronchial cytology, and to report an experience of applying immunocytochemistry on this rare entity. MethodsA multi-institute review of bronchial cytology specimens from histologically proven pulmonary AdCCs was performed. Published cases of bronchial cytology of pulmonary AdCC were reviewed. The cytologic features and immunocytochemical profile for pulmonary AdCC was summarized and compared with pertinent differentials. ResultsA total of 16 specimens from eight patients were retrieved. The initial cytologic diagnoses were negative (n = 7), atypia (n = 6), suspicious (n = 2) and AdCC (n = 1). Retrospective review showed eight bronchial cytology specimens (including five cases of atypia) with tumor cells present. The tumor cells displayed small basaloid nuclei with occasional small nucleoli, mild nuclear atypia, and scanty cytoplasm. Architectural patterns observed included clusters, tubules, solid sheets, three-dimensional balls, papillary-like fronds, and complex cribriform structures. Basement-membrane-like material, free or associated with tumor cells, were seen in all cases. Immunocytochemistry was performed in one specimen. MYB was positive. TTF-1, synaptophysin and chromogranin were negative. Epithelial and basal markers demonstrated a dual cell population. Literature review yielded 28 cases. Cytologic features described were similar except for cytoplasmic vacuolation in one case. ConclusionBasement membrane-like material is specific for AdCC. MYB positivity, TTF-1 and neuroendocrine marker negativity, support a diagnosis of AdCC. Other immunocytochemistry and cytologic features overlap significantly with adenocarcinoma and small cell carcinoma of lung.

A study on clinicopathological spectrum of nodular hidradenoma

<p>Nodular hidradenoma (NH) is an uncommon benign skin adnexal tumor that presents usually as solitary intradermal nodule. This study aims to discuss the various clinicopathological features of NH as it mimics other adnexal tumors, malignancies or metastasis particularly in uncommon sites. Twenty-four cases of histo-pathologically diagnosed NH during study period from 2016 to 2021were taken up for study. Their clinical, gross and microscopic findings were collected from records. Most tumors occurred in head in fifth decade. Cystic change was seen in majority of the cases. Tumor had dual population of cells with predominant clear cell component in five cases. Definitive cytological diagnosis was difficult requiring excision biopsy. Characteristic clinical and histological features help to distinguish NH from other potential mimickers NH need wide excision as they can recur and rarely transform in to malignancy.</p>

Unique Presentation of Bing-Neel Syndrome With Co-existing Chronic Lymphocytic Leukemia.

Unique Presentation of Bing-Neel Syndrome With Co-existing Chronic Lymphocytic Leukemia.

Serous cavity metastasis: Evaluation of unknown primary.

Malignant effusions can occur in patients with neoplasia. Once a metastatic diagnosis is confirmed, the primary site of origin of malignancy needs to be ascertained. This task can be challenging without a prior history of malignancy. In some patients their effusion may be the initial presentation of an underlying malignancy. Metastases usually present with a dual population of mesothelial and malignant cells. Combining cytomorphologic examination with ancillary testing such as immunocytochemistry can help identify the origin of the foreign malignant cell population. Helpful architectural clues include a single cell pattern, solid cell ball pattern, single file arrangement, papillary formation, psammoma bodies and background mucin. Useful cellular features include the presence of signet ring cells, small cells, pleomorphic and multinucleated giant cells, squamous cells, spindle cells and pigmentation. Rarely, despite an extensive work-up the primary site of origin for a malignant effusion may remain unresolved. This review article will be incorporated finally as one of the chapters in CMAS (CytoJournal Monograph/Atlas Series) #2. It is modified slightly from the chapter by the initial authors in the first edition of Cytopathologic Diagnosis of Serous Fluids.

Challenges in the Intraoperative Consultation of Low-Grade Epilepsy-Associated Neuroepithelial Tumors by Cytomorphology in Squash Preparations

Introduction: Low-grade epilepsy-associated neuroepithelial tumors (LEATs) create a diagnostic challenge in daily practice and intraoperative pathological consultation (IC) in particular. Squash smears are extremely useful in IC for accurate diagnosis; however, the knowledge on cytopathologic features of LEATs is based on individual case reports. Here, we discuss the 3 most common and well-established entities of LEATs: ganglioglioma (GG), dysembryoplastic neuroepithelial tumor (DNT), and papillary glioneuronal tumor (PGNT). Methods: Thirty patients who underwent surgery for GG, DNT, and PGNT between 2001 and 2021 were collected. Squash smears prepared during intraoperative consultation were reviewed by 1 cytopathologist and an experienced neuropathologist. Results: Among the 30 tumors, 16 (53.3%) were GG, 11 (36.6%) DNT, and 3 (10%) PGNT. Cytomorphologically, all of the 3 tumor types share 2 common features such as dual cell population and vasculocentric pattern. GG smears were characteristically composed of dysplastic ganglion cells and piloid-like astrocytes on a complex architectural background of thin- to thick-walled vessels. DNT, on the other hand, showed oligodendroglial-like cells in a myxoid thin fibrillary background associated with a delicate capillary network. Common cytological features of PGNT were hyperchromatic cells with narrow cytoplasm surrounding hyalinized vessels forming a pseudopapillary pattern and bland cells with neuroendocrine nuclei dispersed in a neuropil background. Conclusion: A higher diagnostic accuracy can be obtained when squash smears are applied with frozen sections. However, it is important to integrate clinical and radiologic features of the patient as well as to know the cytopathologic features of the LEAT spectrum in the context of differential diagnosis to prevent misinterpretation in the IC.

Spectrum of biphasic renal cell carcinomas with hyalinized stroma and psammoma bodies associated and not associated with NF2 alteration

A unique subtype of biphasic renal cell carcinoma (RCC) was recently described and termed biphasic hyalinizing psammomatous RCC (BHPRCC). This tumor shows a dual population of larger cells and small cells surrounding basement membrane-like materials and invariably has papillary features, hyalinized stroma, and psammoma calcifications. The biphasic pattern in BHPRCC may resemble that of RCC associated with TFEB gene fusion or t (6;11) RCC. However, all reported BHPRCCs had no TFEB alterations and all were associated with neurofibromin 2 (NF2) mutations. Herein, we present three biphasic RCCs encompassing the reported BHPRCC morphologies. One RCC showed solid, nested, papillary, and tubular growths, with biphasic pattern of larger cells surrounding clusters of smaller cells arranged around basement membrane-like materials, and harbored NF2 mutation consistent with BHPRCC. This patient developed bone metastasis 59 months after surgery. The two other biphasic RCCs showed morphologic overlap to BHPRCC, but in addition had other features not seen in BHPRCC, such as lack of papillary pattern, having large tubules containing mucinous to collagenous spherules (mucicarmine and collagen IV positive) bordered by a single layer of small cells with occasional central targetoidpsammoma bodies, and with widespread nuclear grooves. Interestingly, these two tumors also did not show alterations in NF2 or TFEB including translocation or amplification. In conclusion, we report another example of the novel BHPRCC that had metastasized and two biphasic RCCs not associated with NF2 or TFEB alterations; the latter two shared additional distinct morphological features and may represent a unique biphasic RCC distinct from the novel BHPRCC.

CD5-Negative, CD10-Negative Low-Grade B-Cell Lymphoproliferative Disorders of the Spleen.

CD5-negative, CD10-negative low-grade B-cell lymphoproliferative disorders (CD5-CD10-LPD) of the spleen comprise a fascinating group of indolent, neoplastic, mature B-cell proliferations that are essential to accurately identify but can be difficult to diagnose. They comprise the majority of B-cell LPDs primary to the spleen, commonly presenting with splenomegaly and co-involvement of peripheral blood and bone marrow, but with little to no involvement of lymph nodes. Splenic marginal zone lymphoma is one of the prototypical, best studied, and most frequently encountered CD5-CD10-LPD of the spleen and typically involves white pulp. In contrast, hairy cell leukemia, another well-studied CD5-CD10-LPD of the spleen, involves red pulp, as do the two less common entities comprising so-called splenic B-cell lymphoma/leukemia unclassifiable: splenic diffuse red pulp small B-cell lymphoma and hairy cell leukemia variant. Although not always encountered in the spleen, lymphoplasmacytic lymphoma, a B-cell lymphoproliferative disorder consisting of a dual population of both clonal B-cells and plasma cells and the frequent presence of the MYD88 L265P mutation, is another CD5-CD10-LPD that can be seen in the spleen. Distinction of these different entities is possible through careful evaluation of morphologic, immunophenotypic, cytogenetic, and molecular features, as well as peripheral blood and bone marrow specimens. A firm understanding of this group of low-grade B-cell lymphoproliferative disorders is necessary for accurate diagnosis leading to optimal patient management.

Sclerosing microcystic adenocarcinoma of the parotid gland – The first recorded case with histo-cytopathologic correlation and a brief review of the literature

We present a case of a 1.0 cm primary tumor of the left parotid gland that meets the histological criteria for the recently described entity sclerosing microcystic adenocarcinoma. The patient was a 73-year-old man with a concurrent tonsillar squamous cell carcinoma, and a history of nasopharyngeal carcinoma treated with radiotherapy 23 years prior. Fine needle aspiration cytology demonstrated low-grade biphasic basaloid neoplastic cells arranged in branching sheets and clusters with minimal nuclear pleomorphism. A biphasic appearance was apparent and some of the cell clusters were bordered by a layer of flattened cells with ovoid bland nuclei. On histology, the tumor comprised small bilayered infiltrative tubules, nests, cords, and microcysts. On immunohistochemistry, EMA, SOX-10, P63, and S-100 protein highlighted a dual cell population of luminal and abluminal cells. The cells were negative for CD117, and the Ki-67 proliferation index was low (<5%).

Challenging of frozen diagnoses of small sclerosing pneumocytoma

AimsAn increasing number of small pulmonary nodules are being screened by CT, and an intraoperative diagnosis is necessary for preventing excessive treatment. However, there is limited literature on the frozen...

Primary Giant Cell Tumors of the Lung: A Clinicopathologic and Immunohistochemical Study of 3 Cases.

Three cases of primary giant cell tumors of the lung akin to those described in the soft tissues are presented. The patients are 3 men between the ages of 43 and 54 years who presented with nonspecific symptoms of cough, chest pain, and shortness of breath. None of the patients had any prior history of malignancy anywhere else. Diagnostic imaging disclosed the presence of an intrapulmonary mass. All the patients underwent lobectomy. Grossly, the tumors were described as solid, slightly hemorrhagic, and measuring between 1.8 and 2.4 cm in greatest diameter. Histologically, the tumors were characterized by a dual population of multinucleated giant cells admixed with a mononuclear proliferation. Nuclear atypia was mild to moderate, and mitotic activity varied but was under 5 mitotic figures per 10 high power fields. Immunohistochemical stains showed positive staining for vimentin, CD68, and cathepsin K, whereas the tumors were negative for keratin, TTF-1, p40, S-100 protein, and SABT-2. Clinical follow-up was obtained in 2 patients who have remained alive and without evidence of recurrence or metastasis up to 12 months after surgery. One patient was lost to follow-up. The current neoplasms represent a tumor that to the best of our knowledge has not been reported as a primary neoplasm of the lung. The cases herein described represent an unusual occurrence and should be maintained in the differential diagnosis of primary pulmonary tumors rich in multinucleated giant cells.

Expanding the morphologic spectrum of chromophobe renal cell carcinoma: A study of 8 cases with papillary architecture

Although typically arranged in solid alveolar fashion, chromophobe renal cell carcinoma (RCC) may also show several other architectural growth patterns. We include in this series 8 chromophobe RCC cases with prominent papillary growth, a pattern very rarely reported or only mentioned as a feature of chromophobe RCC, which is lacking wider recognition The differential diagnosis of such cases significantly varies from the typical chromophobe RCC with its usual morphology, particularly its distinction from papillary RCC and other relevant and clinically important entities.Of 972 chromophobe RCCs in our files, we identified 8 chromophobe RCCs with papillary growth. We performed immunohistochemistry and array Comparative Genomic Hybridisation (aCGH) to investigate for possible chromosomal aberrations.Patients were 3 males and 5 females with age ranging from 30 to 84 years (mean 57.5, median 60 years). Tumor size was variable and ranged from 2 to 14 cm (mean 7.5, median 6.6 cm). Follow-up was available for 7 of 8 patients, ranging from 1 to 61 months (mean 20.1, median 12 months). Six patients were alive with no signs of aggressive behavior, and one died of the disease. Histologically, all cases were composed of dual cell population consisting of variable proportions of leaf-like cells with pale cytoplasm and eosinophilic cells. The extent of papillary component ranged from 15 to 100% of the tumor volume (mean 51%, median 50%). Sarcomatoid differentiation was identified only in the case with fatal outcome. Immunohistochemically, all tumors were positive for CK7, CD117 and Hale's Colloidal Iron. PAX8 was positive in 5 of 8 cases, TFE3 was focally positive 3 of 8 tumors, and Cathepsin K was focally positive in 2 of 8 tumors. All cases were negative for vimentin, AMACR and HMB45. Fumarate hydratase staining was retained in all tested cases. The proliferative activity was low (up to 1% in 7, up to 5% in one case). Three cases were successfully analyzed by aCGH and all showed a variable copy number variation profile with multiple chromosomal gains and losses. ConclusionsChromophobe RCC demonstrating papillary architecture is an exceptionally rare carcinoma. The diagnosis can be challenging, although the cytologic features are consistent with the classic chromophobe RCC. Given the prognostic and therapeutic implications of accurately diagnosis other RCCs with papillary architecture (i.e., Xp11.2 translocation RCC, FH-deficient RCC), it is crucial to differentiate these cases from chromophobe RCC with papillary architecture. Based on this limited series, the presence of papillary architecture does not appear to have negative prognostic impact. However, its wider recognition may allow in depth studies on additional examples of this rare morphologic variant.

SPREADING OF GLANDULAR MALIGNANCY MIMICKING BONE LESION: REPORT OF TWO CASES

Peripheral nerves are target for local invasion and spreading in pancreatic, gastric, prostate, and head and neck cancers. Adenoid cystic carcinoma (ACC) accounts less than 10% of salivary gland neoplasms with dual cell population, typically exhibiting three architectural patterns. Distant metastasis and neural involvement are common clinical features. Objectives To report two rare cases of ACC arising from parotid gland and extending into mandible through mandibular foramen. Results A 50-year-old woman and 49-year-old man presented with pain and parestesia in the left face. A swelling was observed and computed tomography detected osteolytic lesion with irregular margins involving complete body and ramus in the left side of the mandible. Clinical diagnosis was established of osteomyelitis and sarcoma. Microscopically, both tumors presented as solid masses with few ductiform structures. Tumor cells had basaloid appearance with large pleomorphic and prominent nuclei or densely hyperchromatic with scant cytoplasm. Frequent mitotic figures and comedolike necrosis were seen. Tumor infiltration was detected in the perineurial region of the inferior alveolar nerve and within bone medula. In one case, tumor cells has spread to the dental pulp. Immunohistochemically, tumor cells in one case were positive for CK7, 34BE1, CD117, Ki67 (>5 in 10hpf) and negative for p63 and CK5/6. Conclusion Two rare cases of mandibular extension of a parotid gland ACC through the mandibular foramen is presented. Computed tomography and magnetic resonance confirmed primary ACC in the parotid gland, suggesting access of tumor cells through mandibular canal. Meticulous clinical and radiographic analysis were essential to detect primary tumor for an appropriate therapy.

Human Papillomavirus-Related Carcinoma With Adenoid Cystic-like Features of the Sinonasal Tract (Also Known as Human Papillomavirus-Related Multiphenotypic Sinonasal Carcinoma).

Human papillomavirus (HPV)-related carcinoma with adenoid cystic-like features is a rare, recently recognized entity restricted to the sinonasal tract. By definition, it is associated with high-risk HPV infection, particularly with HPV type 33. In most cases, tumors are composed of dual cell populations, including predominant basaloid myoepithelial cells and usually inconspicuous ductal cells. Solid components with focal cribriform or tubular patterns, abrupt keratinization within tumor nests, and squamous dysplasia of the surface epithelium are characteristics of HPV-related carcinoma with adenoid cystic-like features. The immunohistochemistry of p16 followed by high-risk HPV testing may help in the differential diagnosis. Recent studies have demonstrated that the morphologic features of this entity are more diverse than initially believed. Surgical resection is the prime alternative for treatment. According to the limited data, the prognosis of this disease may be better than that of other sinonasal carcinomas.

Histological findings and pathologic diagnosis of spiradenocarcinoma: A case series and review of the literature.

Atypical spiradenoma and spiradenocarcinoma present a diagnostic challenge. We aim to assess the significance of certain histologic features, which may facilitate diagnosis of these tumors. A natural language search for cases of "atypical spiradenoma" and "spiradenocarcinoma" diagnosed between 2009 and 2018 was performed. Original slides were retrieved and a subset of cases (n = 5) were stained for Ki-67, p53, carcinoembryonic antigen (CEA), and S100. All cases (n = 7) were assessed for overall architecture, atypical mitotic figures, abnormal cytology, necrosis, ductal proliferation, dilated vessels, and loss of dual cell population. All our cases showed an abrupt transition from benign to malignant morphology, nuclear atypia, atypical mitotic figures, and a monomorphic loss of the dual cell population (7/7; 100%). The majority also had dilated vessels (6/7; 85.7%), and ductal dilation or proliferation (5/7; 71.4%). Fewer cases showed tumor encapsulation (3/7; 43%), massive necrosis (3/7; 43%), and focal cellular necrosis (1/7; 14%). All cases showed a relatively increased Ki-67 proliferation index at the transitional interface (5/5; 100%). Almost all cases stained positively for p53 (4/5; 80%). Malignant areas of tumor or at the transitional interface showed more intense S100 staining (3/5; 60%). All cases were negative for CEA. Histologic features that strongly favor atypical spiradenoma or spiradenocarcinoma include abrupt transition to malignant foci, atypical mitotic figures, and monomorphic loss of the dual cell population. Ki-67, p53, and S100 may help delineate areas of atypical or malignant transformation in spiradenomas.

Melanotic neuroectodermal tumor of infancy: A rare case report

Melanotic neuroectodermal tumor of infancy (MNTI) is a very rare neoplasm of infants seen in the oral cavity at or around birth. It shows rapid expansile growth which necessitates proper diagnosis and management. A 6.5-month-old female child reported with a swelling in the maxillary anterior alveolus, which was rapidly increasing in size and was asymptomatic. Radiographic examination showed a diffuse osteolytic radiolucent lesion in the anterior maxillary region and displacement of the developing primary tooth buds. Ultrasonography report revealed well-defined cystic lesion with calcifying foci within and with no internal vascularity. Wide surgical excision under general anesthesia was performed. Histopathological report revealed a nonencapsulated mass composed of a dual population of small round blue cells and larger melanin-containing epithelial cells in a dense cellular fibrous stroma. Tumor is seen to entrap mature bony trabeculae and soft tissue on the whole favoring a diagnosis of MNTI. Early recognition and regular follow-up is the key to successful treatment.

Phenotypic variation of thymic epithelial cells and partial spontaneous regression in thymoma of a cow

Thymoma was recognized in a 12-year-old Holstein dairy cow presenting with no significant clinical signs. The animal was conventionally slaughtered at an abattoir and, on postmortem examination, a spherical tumor mass was found in the anterior region of the mediastinum. Histologically, the tumor was fibrously encapsulated and exhibiting varying-sized cystoid cavities containing serous fluid and necrotic and hemorrhagic foci. No architectural features showing distinct characteristics to a sufficient degree to allow identification of the thymus or other organs could be seen. The tumor showed diffuse solid sheet-like or nodular patterns of proliferation and consisted of a dual cell population: one was neoplastic epithelial cells that were immunohistochemically positive for cytokeratin, and the other was T lymphocytes that exhibited positive immunohistochemical staining with CD3. This finding enabled a diagnosis of mixed thymoma to be made. Neoplastic epithelial cells represented a wide spectrum of phenotypic expression, including (1) spindle shaped cells with a chiasmus-like, interlacing fascicular, or storiform growth pattern; (2) small, round to oval cells with scant cytoplasm showing indistinct boundary of cells; (3) large cells arranged in a solid sheet-like pattern; (4) vacuolated cells similar to signet ring cells; (5) clear cells that had defined cell membranes; and (6) occasional formation of micronodules composed of neoplastic epithelial cells. In addition, some areas of the tumor exhibited features of partial spontaneous regression characterized by collapse or disintegration of tumor tissues in close association with fibrocollagenous connective tissue deposition. Even if the morphology of thymic epithelial cells in thymoma is known to display variable appearance, it is likely to be unusual that, in the current bovine case, such thymic epithelial cells exhibited a wider spectrum of phenotypic expression within a single tumor. This salient histomorphological heterogeneity shown by thymic epithelial cells might have presumably been associated with innate characteristics specific to pluripotent thymic epithelial cells during thymoma tumorigenesis.