Granular Eosinophilic Cytoplasm Research Articles

New insights into acinic cell carcinoma of the breast: clinicopathology, origin of histology, molecular features, prognosis, and treatment

Acinic cell carcinoma (AciCC) of the breast is a rare malignant epithelial neoplasm, with approximately 60 cases reported in the literature. It predominantly affects women and exhibits significant histological heterogeneity. The diagnosis of breast AciCC is primarily based on the presence of eosinophilic and/or basophilic granular cytoplasm and markers of serous acinar differentiation. Despite being considered a low-grade variant of conventional triple-negative breast cancer (TNBC), over 25% of patients with breast AciCC have adverse clinical outcomes. Additionally, in early research, microglandular adenosis (MGA) and atypical MGA were considered potential precursors for various breast cancers, including intraductal carcinoma, invasive ductal carcinoma, adenoid cystic carcinoma, metaplastic carcinoma, and AciCC. Similarly, some studies have proposed that breast AciCC should be considered a type of carcinoma developing in MGA with acinic cell differentiation rather than a distinct entity. Therefore, the pathogenesis of breast AciCC has not yet been clarified. Moreover, to the best of our knowledge, the literature has not summarized the latest prognosis and treatment of breast AciCC. In this review, we synthesized the current literature and the latest developments, aiming at exploring the clinicopathology, histological origin, molecular features, prognosis, and treatment of breast AciCC from a novel perspective.

Clear Cell Renal Cell Carcinoma: A Comprehensive Review of its Histopathology, Genetics, and Differential Diagnosis.

Clear cell renal cell carcinoma (ccRCC) is the predominant subtype of renal epithelial tumor, accounting for roughly 2% of all malignancies. Clinically, it often presents in the sixth to seventh decade of life, predominantly in men. Pathologically, these tumors exhibit a distinctive golden yellow cut surface, usually arising from the renal cortex. Their microscopic features are characterized by solid and nested architectures of cells with clear or eosinophilic granular cytoplasm and a prominent vascular network. A hallmark genetic feature is the inactivation of the VHL gene situated on chromosome 3p25. The majority of ccRCCs are sporadic (over 95%), typically presenting as a single mass; and a small percentage have a hereditary basis, often associated with VHL disease, characterized by multiple bilateral tumors with an earlier onset. Immunohistochemically, ccRCC tumors express PAX8, CA9 box like pattern, and CD10 but are generally negative for AMACR (35% positive) and KRT7 (15% positive). The prognosis of ccRCC is largely determined by its TNM stage, ISUP/WHO nucleolar grade, and the presence of specific aggressive features. This review article delves into the detailed gross, microscopic, molecular, and clinical features of ccRCC, offering comprehensive insights into its diagnosis, management, and prognosis.

Pancreatic neuroendocrine tumor with abundant mitochondria.

A 40-year-old woman presented with dull, boring periumbilical region pain radiating to the back and vomiting for 1 year. Magnetic resonance cholangiopancreatography detected a polypoid growth in the ampullary region. The patient underwent Whipple's procedure. The specimen revealed a 4.9 × 4.5 × 3.7 cm tumor arising from the pancreas, abutting the posterior pancreatic surface and infiltrating the terminal common bile duct and the ampulla. Microscopic examination showed a pancreatic tumor composed of neuroendocrine cells. In addition, many large foci showing solid sheets of oncocytic cells with abundant granular eosinophilic cytoplasm were observed. Immunohistochemistry studies revealed positivity for synaptophysin, chromogranin, and Ki67 index above 70%. A diagnosis of oncocytic neuroendocrine tumor of Grade 3 was made. In electron microscopy, oncocytic cells showed abundant mitochondria dispersed throughout the cytoplasm. Oncocytic pancreatic neuroendocrine neoplasms are uncommon and can be diagnosed only on histopathological examination. These tumors tend to show a malignant behavior.

Pure Apocrine Intraductal Carcinoma of Salivary Glands: Reassessment of Molecular Underpinnings and Behavior.

Intraductal carcinoma (IDC) of the salivary glands is a confounding entity, our understanding of which continues to evolve. At least four forms have been elucidated based on histomorphology, immunophenotype, and molecular profile: (1) intercalated duct-like, S100/SOX10+ with frequent NCOA4::RET fusions; (2) oncocytic, S100/SOX10+ with TRIM33::RET, NCOA4::RET, and BRAF V600E; (3) apocrine, AR+ with PI3 kinase pathway mutations; and (4) mixed/hybrid intercalated duct-like/apocrine, with S100/SOX10+ and AR+ areas and frequent TRIM27::RET. The revelation that myoepithelial cells harbor the same fusion as luminal cells suggested that fusion-positive cases are not in situ carcinomas as previously believed. To this point, purely apocrine IDC with entirely intraductal growth has not been found to harbor fusions, but very few cases have been tested. IDCs with pure apocrine morphology, entirely intraductal growth, and no precursor lesion (pleomorphic adenoma or sclerosing polycystic adenoma) were retrieved from the authors' archives. Several immunostains (S100, SOX10, GCDFP-15, AR, p40/SMA) and targeted next generation sequencing (NGS) panel including 1425 cancer-related genes were performed. Seven entirely IDC with pure apocrine type were collected. The cases arose in the parotid glands (mean, 1.9 cm) of 5 men and 2 women ranging from 51 to 84 years (mean, 69.7 years). Histologically, tumors consisted of rounded to angulated ductal cysts lined by epithelial cells with abundant finely granular eosinophilic cytoplasm and large nuclei with prominent nucleoli. Pleomorphism was mild to moderate, the mitotic rate was low, and necrosis was absent. Conventionally invasive foci or areas of intercalated duct-like morphology were not identified. In all cases, luminal cells were diffusely positive for AR and GCDFP-15 while negative for S100/SOX10, and the ducts were completely surrounded by myoepithelial cells highlighted by p40 and SMA. Molecular analysis was successful in 6 cases. Three harbored fusions: one with NCOA4::RET, another with STRN::ALK and one with both CDKN2A::CNTRL and TANC1::YY1AP1. The three fusion-negative cases all harbored HRAS mutations; additional mutations (PIK3CA, SPEN, ATM) were found in 2 of 3 cases. All patients were treated by surgery alone. Six of them are currently free of disease (follow up 12-190 months), but the case harboring NCOA4::RET developed lymph nodes metastasis in the form of a fusion-positive invasive salivary duct carcinoma. Purely apocrine IDC is a heterogeneous disease. A subset seems to be genetically similar to salivary duct carcinoma and may indeed represent carcinoma in situ. The other group harbors fusions, similar to other forms of IDC. Moreover, the occurrence of lymph node metastasis discredits the idea that any fusion-positive IDC with a complete myoepithelial cell layer has no metastatic potential. With the wide use of RET-and ALK-based targeted therapies, our findings further underscore the importance of fusion analysis for IDC.

A rare case malignant granular cell tumor of the thigh with radiological imaging likely rhabdomyosarcoma: A case report

Granular cell tumors (GCTs) are uncommon soft tissue tumors characterized by the cytoplasmic granular appearance of the neoplastic cells. Malignant GCTs are rare neural tumors, intensely aggressive. Both the rare occurrence of malignant GCTs and its similarities in features with their benign lesions make the diagnosis of this malignancy difficult. Malignant GCTs comprise less than 2% of GCTs and are mostly found in the subcutaneous soft tissues of the lower extremities, especially the thighs. This article presents a case of a large malignant GCTs in the left thigh of a 46-year-old woman. Plain radiograph of the left thigh demonstrated a soft tissue mass without bone involvement. MRI images showed a malignant solid mass 7.8 x 5.2 x 21.6 cm, with ill-defined border, irregular edges, and suspected rhabdomyosarcoma. Incisional biopsy of the mass lesion revealed mixed epithelioid and spindle tumors, suspected malignant GCTs. Histological examination performed by a musculoskeletal pathologist, demonstrated nests and sheets of epithelioid to polygonal cells with hyperchromatic, intensely eosinophilic granular cytoplasm, prominent nucleoli, increased mitotic activity, necrosis, areas of spindling with significant atypia, and positive for S100 by immunohistochemistry. In conclusion, this patient with malignant soft tissue tumor demonstrated polygonal and spindle cells with eosinophilic granular cytoplasm, which need to be considered diagnosed as Malignant GCTs. This case stresses the importance of thorough histological examination in the diagnosis of malignant GCTs.

Malakoplakia of the Endometrium: A Rare Unexpected Disease Raising Clinical Concern for Malignancy.

Malakoplakia is a rare disease that manifests as a histiocytic inflammatory process and most often occurs in the urinary bladder. It is caused by an impaired capacity of histiocytes to kill and digest bacteria. The typical histopathologic findings are sheets of histiocytes with granular eosinophilic cytoplasm and characteristic Michaelis-Gutmann bodies, spherical bodies with a targetoid appearance. Malakoplakia is even rarer in the gynecologic tract, and our literature search found only 21 published patients of malakoplakia involving the endometrium. Here we report a 60-year-old female patient who presented with recurrent pelvic infections and postmenopausal bleeding, which raised concern for an endometrial malignancy. Hysterectomy with salpingo-oophorectomy revealed malakoplakia involving the endometrium and also the right ovary. Michaelis-Gutmann bodies were visible on the intraoperative frozen section that was performed to rule out an endometrial malignancy. We summarize the clinicopathologic findings of the published patients of endometrial malakoplakia.

Carotid body tumors: a review

Carotid body tumor or paraganglioma, is located periadventitially in relation to the carotid bifurcation. Generally, the blood supply of carotid tumors is abundant, it comes mainly from the branches of the external carotid arteries, although cases have been reported where the irrigation comes from the internal carotid artery, vertebral artery, ascending pharyngeal artery and superior thyroid. Although its etiology is unknown, different factors have been associated that contribute to its incidence, such as genetic factors and states of chronic hypoxia. Histologically, they are well vascularized tumors. Between the capillaries there are groups of tumor cells known as Zellballen's pseudoalveolar pattern. These are cells with eosinophilic granular cytoplasm and small round or oval nuclei. The tumor is mobile, but with limitation to mobilization in the cephalocaudal direction. The mass can transmit the carotid pulse due to its proximity to the carotid, and it may also be accompanied by a murmur or thrill. Usually the carotid glomus is identified by clinical examination, so consideration of multiple differential diagnoses. The treatment of choice is surgical excision. The need for preoperative embolization is controversial. Embolization before surgery is recommended to improve surgical success with reduced blood loss as well as reduce the risk of cranial nerve injury. The decision to perform presurgical embolization or not depends on the surgeon.

A case of pancreatic PEComa with prominent inflammatory cell infiltration: the inflammatory subtype is a distinct histologic group of PEComa

BackgroundPEComa is a mesenchymal tumor that can occur in various organs including the uterus and soft tissues. PEComas are composed of perivascular epithelioid cells, and angiomyolipoma (AML), clear cell sugar tumor (CCST), and lymphangiomyomatosis (LAM) are considered lesions of the same lineage as tumors of the PEComa family. Histologically, a common PEComa shows solid or sheet-like proliferation of epithelioid cells. This is accompanied by an increase in the number of dilated blood vessels. Here, we report a case of pancreatic PEComa with marked inflammatory cell infiltration.Case presentationA 74-year-old male patient underwent an appendectomy for acute appendicitis. Postoperative computed tomography and magnetic resonance imaging revealed a 30 × 25 mm non-contrast-enhanced circular lesion in the tail of the pancreas. The imaging findings were consistent with a malignant tumor, and distal pancreatectomy was performed. Histologically, most area of the lesion was infiltrated with inflammatory cells. A few epithelioid cells with large, round nuclei, distinct nucleoli, and eosinophilic granular cytoplasm were observed. Spindle-shaped tumor cells were observed. Delicate and dilated blood vessels were observed around the tumor cells. Immunohistochemically, the atypical cells were positive for αSMA, Melan A, HMB-45, and TFE3. The cytological characteristics of the tumor cells and the results of immunohistochemical staining led to a diagnosis of pancreatic PEComa.ConclusionsA histological variant known as the inflammatory subtype has been defined for hepatic AML. A small number of tumor cells present with marked inflammatory cell infiltration, accounting for more than half of the lesions, and an inflammatory myofibroblastic tumor-like appearance. To our knowledge, this is the first report of pancreatic PEComa with severe inflammation. PEComa is also a generic term for tumors derived from perivascular epithelioid cells, such as AML, CCST, and LAM. Thus, this case is considered an inflammatory subtype of PEComa. It has a distinctive morphology that is not typical of PEComa. This histological phenotype should be widely recognized.

Characterization of a Molecularly Distinct Subset of Oncocytic Pleomorphic Adenomas/Myoepitheliomas Harboring Recurrent ZBTB47-AS1::PLAG1 Gene Fusion.

Recurrent gene fusions are common in salivary gland tumors including benign tumors, such as pleomorphic adenoma (PA) and myoepithelioma (ME). In cases where chromosomal rearrangement is identified in the pleomorphic adenoma gene 1 (PLAG1) gene, different gene partners are found. Oncocytic metaplasia, characterized by oncocytes with abundant eosinophilic granular cytoplasm and hyperchromatic nuclei, is a well-known phenomenon in salivary gland neoplasms. However, the pure oncocytic variant of PA/ME showed PLAG1 gene rearrangements involving various gene partners at the molecular level, without any recurrent fusion being found. Our study includes 20 cases of PA/ME, with 11 females and 9 males. The age of patients ranged from 37 to 96 years, with a median age of 62.8 years. Most tumors originate from the parotid gland. The median size of the tumor was 26.5 mm (range: 13 to 60 mm). Among the 20 cases, 14 were a pure oncocytic variant of PA/ME, whereas 6 cases showed focal oncocytic or oncocytic-like aspects. Molecular studies on 20 cases of PA/ME were conducted. A novel recurrent ZBTB47-AS1::PLAG1 fusion was identified in 6 of 12 cases with pure oncocytic metaplasia, whereas the other cases had PLAG1 gene fusion with different gene partners. The transcriptomic analysis of the cases harboring ZBTB47-AS1::PLAG1 fusion demonstrated that these tumors have a distinct molecular profile from conventional PA/ME. This study reveals a unique subset in the oncocytic PA/ME spectrum characterized by pure oncocytic morphology with larger oncocytic cells and recurrent ZBTB47-AS1::PLAG1 fusion. It also highlights the transcriptomic distinctness of salivary gland adenomas with pure oncocytic metaplasia in the spectrum of salivary gland neoplasms. Further studies are needed to better understand the oncocytic variant of PA/ME and to determine the true nature of oncocytic cells in PA/ME.

Multiple Congenital Granular Cell Epulis Involving Different Parts of the Oral Cavity: A Case Report.

Congenital granular cell epulis (CGCE) is a rare disease, particularly when it affects multiple oral and maxillofacial regions. We present the case of a female neonate with 4 asymptomatic masses attached to the maxillary and mandibular gingiva as well as the tongue. Due to the size of the masses causing feeding and respiratory difficulties, lesion removal was performed under general anesthesia. Histopathological analysis revealed tightly arranged polygonal cells with abundant granular eosinophilic cytoplasm. Immunohistochemically, the cells were negative for Smur100 (S-100), neuron-specific enolase (NSE), cluster of differentiation (CD) 68, and Sry-related HMG box (SOX)-10, and positive for alpha-1-antitrypsin (AAT) and vimentin. The diagnosis of multiple CGCEs was established through clinical examinations, histomorphometrical, and immunohistochemical analyses. In conclusion, CGCE should be considered in the differential diagnosis of intraoral lesions in neonates.

Neoplastic Progression in Macroscopic Precursor Lesions of the Pancreas.

Macroscopic precursor lesions of the pancreas represent a complex clinical management problem. Molecular characterization of pancreatic cysts has helped to confirm and refine clinical and pathologic classifications of these lesions, inform our understanding of tumorigenesis in the pancreas, and provide opportunities for preoperative diagnosis. To review the pathologic classification of macroscopic cystic lesions of the pancreas: intraductal papillary mucinous neoplasms (IPMNs), mucinous cystic neoplasms (MCNs), intraductal oncocytic papillary neoplasms (IOPNs), and intraductal tubulopapillary neoplasms (ITPNs), and to describe our current state of understanding of their molecular underpinnings, relationship to invasive carcinomas, and implications for diagnosis and prognostication. We assessed the current primary literature and current World Health Organization Classification of Digestive System Tumours. Macroscopic cystic lesions of the pancreas are morphologically and molecularly diverse. IPMNs and MCNs share mucinous cytoplasm with papillae. MCNs are defined by ovarian-type stroma. IOPNs have granular eosinophilic cytoplasm, prominent nucleoli, and complex, arborizing papillae. ITPNs demonstrate complex, back-to-back tubules and anastomosing papillae and lack prominent intracellular mucin. IPMNs and MCNs are characterized by driver mutations in KRAS/GNAS (IPMNs) and KRAS (MCNs), with later driver events in RNF43, CDKN2A, SMAD4, and TP53. In contrast, IOPNs and ITPNs have recurrent rearrangements in PRKACA/PRKACB and MAPK-associated genes, respectively. The recurrent alterations described in cysts provide an opportunity for diagnosis using aspirated cyst fluid. Molecular characterization of IPMNs shows a striking spatial and mutational heterogeneity, challenging traditional models of neoplastic development and creating challenges to interpretation of cyst fluid sequencing results.

Intra-adrenal Paraganglioma and Paraaortic Paraganglioma in 15 Years Old Boys

Intra-adrenal paraganglioma (also called pheochromocytoma) is a chromaffin cell tumor that arises in the adrenal medulla and produces excess catecholamines. Paraganglioma can also be located in the extra-adrenal area. The incidence rate of intra-adrenal and extra-adrenal paraganglioma is about 1 case per 2.500-6.500 population, highest incidence at 40-50 years old, and distribution is the same in males and females. Intra-adrenal paraganglioma in pediatrics is more familial, bilateral, multifocal, and malignant. In children, the incidence rate of these tumors was 8.86%, the ratio of boys to girls was 2:1, and the average age of 11. This article reports a case, of a 15 years old boy with severe headaches, recurrent seizures, and a hypertension crisis (143/103-220/110 mmHg). MSCT scan of abdominal showed solid mass heterogeneous with central necrotic multiple in the supero-anterior of the left and right kidneys and on the right anterolateral aorta as high as CV L2, impressive adrenal gland mass and extra-adrenal, suspect pheochromocytoma. Performed surgery, routine histopathological examination, and Immunohistochemistry. Macroscopic examination showed an oval round shape mass of left and right adrenal tumors as well as the paraaortic, a smooth outer surface of the capsular, with yellowish brown color mass tumor at cut surface, supple consistency. Microscopic examination showing adrenal gland and paraaortic tissue with fibrous capsule contains proliferation of neoplastic cells forming a nested alveolar (Zellballen) pattern with a round oval to polygonal cells, granular eosinophilic cytoplasm, round oval nuclei, surrounded by sustentacular cells. Chromogranin A and S-100 are positive. The case was concluded by clinical findings, histopathological, and immunohistochemistry as intra-adrenal paraganglioma and paraganglioma of paraaortic.

A Case of a Granular Cell Tumor Arising in a Patient with Long-segment Barrett's Esophagus.

Esophageal cell tumors are rare. Esophagogastroduodenoscopy performed on a 48-year-old woman revealed an elevated esophageal lesion and the presence of long-segment Barrett's esophagus. Endoscopic ultrasonography showed a 15 mm homogeneous hypoechoic tumor extending from the lamina propria mucosa to the submucosa. Pathological examination of the biopsy tissue revealed a sheet-like cluster of histiocytoid cells with an abundant eosinophilic granular cytoplasm. Immunohistochemical examination revealed S-100 (+) and CD68 (+), thus suggesting the diagnosis of a granular cell tumor. The tumor was resected by endoscopic submucosal dissection. Pathologically, the background mucosa was Barrett's mucosa. This is the first reported case of an esophageal granular cell tumor in long-segment Barrett's esophagus.

A Rare Case of Granular Cell Tumour of Tongue in a 13-year-old Girl

Granular Cell Tumour (GCT) is a rare benign tumour that usually affects adults in the third to sixth decades, with females being more commonly affected. Here, a rare case of GCT occurring in a 13-year-old child is presented. A young girl presented with a painless swelling on the right-side of her tongue. Her past medical history was unremarkable. Upon examination, a firm, well-defined, non pulsatile, non tender lesion measuring 1×0.8 cm was noted, involving the right lateral border of the tongue. The lesion was excised and sent for histopathological examination. Gross examination revealed a 1×0.8×0.6 cm mass with a grey-white cut surface. Microscopy showed hyperplastic stratified squamous epithelium overlaying a submucosal tumour composed of polygonal cells arranged in sheets. The tumour cells had central small round nuclei with abundant granular eosinophilic cytoplasm and intervening skeletal muscle fibres. No necrosis, atypia, or increased mitosis were observed. Immunohistochemistry showed strong nuclear positivity and bright granular cytoplasmic positivity for S-100, confirming the diagnosis of GCT. The patient was followed-up for 14 months after surgery and reported no recurrences. GCTs typically manifest in older individuals, with the highest prevalence in the fifth and sixth decades of life. However, this case deviates from the norm, being noted in a 13-year-old child. This exceptionally unusual presentation should prompt the inclusion of GCT in the differential diagnosis of tongue neoplasms in paediatric patients as well. Periodic follow-up of these patients is recommended to detect malignant transformations and late recurrences at early stages.

Granular Cell Tumor: An Unusual Cause of Common Peroneal Neuropathy

Granular cell tumors, also known as Abrikossoff’s tumors, are rare soft-tissue tumors, and their occurrence in the peripheral nerves has been very rarely reported. We present the case of a 35-year-old woman with common peroneal neuropathy due to a granular cell tumor, who complained of foot dragging. Common peroneal neuropathy was confirmed by electrophysiology. The tumor mass was observed using ultrasonography and magnetic resonance imaging. The tumor was surgically excised, the tumor cells stained positive for S-100, and eosinophilic granular cytoplasm was observed using microscopy. To the best of our knowledge, this is the first report of a granular cell tumor involving the common peroneal nerve.

Rhabdomyoma of the Oral Cavity Mimicking Reactive Lesions: A Case Report and Review of the Literature.

Extracardiac rhabdomyoma is a tumor that rarely occurs in head and neck region. Adult and fetal types of extracardiac rhabdomyoma are diagnosed only by histopathological examination. In the oral cavity, this lesion usually affects the mouth floor and tongue. Despite the low incidence, adult rhabdomyoma should be considered in the differential diagnosis of oral cavity lesions, and histopathological evaluation might be helpful for the final diagnosis. This study aims to report a rare case of rhabdomyoma mimicking reactive lesions and review the literature. A 34-year-old male was referred to the pathology department with a yellowish sessile lesion in the labial maxillary vestibule. During an excisional biopsy, a mass of unencapsulated soft tissue beneath the vestibular mucosa was observed. The yellowish color in clinical features has led to lipoma as the initial clinical diagnosis. The histological examination exhibited an encapsulated, well-circumscribed benign neoplasm composed of multiple lobules of large polygonal cells with prominent abundant granular eosinophilic cytoplasm. No cellular atypia was observed. Diagnosis of the adult type of rhabdomyoma was made by collective agreement. Rhabdomyoma can be mistaken for other reactive lesions and may resemble their appearance.

Intraparotid Ganglioneuroma: A rare case report.

Introduction: Ganglioneuromas (GNs) are slow-growing, benign tumors arising from Schwann cells, gangliocytes, and neuronal tissues. Case Presentation: We report a rare intraparotid ganglioneuroma in a 42-year-old female presented with a parotid mass. The onset of the lesion dated back to 2021, but the growth was remarkable only in November 2022. The FNA suggested a plexiform neurofibroma. The post-surgical microscopic examination of the excised lesion revealed neoplastic large, rounded cells with abundant, finely granular eosinophilic cytoplasm and a large, eccentric nucleus with a prominent nucleolus as well as fasciculated, with an elongated cytoplasm with fine fibrillar extensions. No mitosis or tumor necrosis was observed. The periphery of the tumor showed perineural entrapment. The immunohistochemical staining for S100 protein, synaptophysin, and chromogranin A were positive. However, the neoplastic cells showed no immunoreactivity for cytokeratin (CK5/6, CK7, AE1/AE3), epithelial membrane antigen, HMB45, Melan A, CD30, CD117 and p40. The case was signed out as mature intraparotid ganglioneuroma. Conclusion: The treatment of choice was surgical resection without adjuvant radiotherapy. No recurrence or post-surgical complications were hitherto reported. To the best of our knowledge, this is the first reported case of intraparotid ganglioneuroma. Caution should be taken not to diagnose this benign neoplasm as a metastasis (e.g. metastatic neuroblastoma) or to request unnecessary overtreatment (e.g., postoperative chemotherapy and radiotherapy).

Mycobacterial Spindle Cell Pseudotumor of the Nasal Cavity.

Mycobacterial spindle cell pseudotumor (MSCP) represents an uncommon tumor-like proliferation associated with nontuberculous mycobacterial infection, i.e., M. avium intracellulare, affecting primarily the lymph nodes of immunocompromised men in their 5th decade. Involvement of the nasal cavity by MSCP is exceedingly rare with only 3 well-documented examples in the literature. A 74-year-old, HIV-negative, man presented with a 0.5-cm nodule of the left nasal cavity clinically presenting as a "nasal polyp." His medical history was significant for colonic adenocarcinoma, cutaneous basal cell carcinoma, and chronic lymphocytic leukemia (CLL) transforming to B-cell prolymphocytic leukemia, responsive to chemotherapy. The patient was diagnosed with prostatic adenocarcinoma treated with radiotherapy two months before the nasal lesion was detected. No lymph node enlargement, pulmonary involvement or hepatosplenomegaly were noticed. The nasal nodule was surgically excised and histopathologically examined to rule out metastatic disease or CLL relapse. Microscopically, the lesion comprised a well-circumscribed, monotonous, spindle cell population in a vaguely storiform arrangement mixed with a heavy infiltrate of neutrophils and sparse lymphocytes. The spindle cells featured finely granular rich eosinophilic cytoplasm with rounded, oval to epithelioid, or elongated nuclei with vesicular chromatin and one or two distinct nucleoli. The lesional cells lacked overt cytologic atypia and showed occasional regular mitoses. The surface epithelium was intact or focally ulcerated. By immunohistochemistry, the spindle cell population stained strongly and diffusely for CD68 and was negative for AE1/AE3, SMA, CD34, and PSA. CD3 highlighted scattered lymphocytes. Ziehl-Neelsen stain disclosed numerous intracytoplasmic acid-fast bacilli. A diagnosis of MSCP was rendered. No recurrences were observed during a 24-month follow-up period. Although exceptionally rare, MSCP should be considered in the differential diagnosis of nodular lesions of the nasal cavity that are characterized microscopically by marked spindle cell proliferation in a vague storiform pattern, admixed with a lymphocytic or mixed inflammatory infiltrate. A negative medical history for HIV infection and medication-induced immunosuppression should not preclude a diagnosis of MSCP, particularly in extranodal sites. Once the diagnosis is established, prognosis appears to be excellent for nasal MSCP following conservative surgical excision.

Abstract 1518: Benign oncocytic tumors in the setting of HLRCC syndrome

Abstract Background: Renal cell carcinomas developing in patients with HLRCC syndrome are known to be aggressive single tumors of variable sizes, with a well-established morphology. Other morphological tumor types occurring in association with classic HLRCC tumors as independent neoplasias in this syndrome, have not been clearly recognized and described. We describe four patients with known HLRCC syndrome with confirmed germ line mutation who developed benign oncocytic renal tumors. Since HLRCC can also be oncocytic in many instances, it is important to be aware of the possible benign oncocytic tumors in this patient group. Design: Four patients with known positive germ line FH mutation and known HLRCC syndrome developed associated or new oncocytic tumors. All tumors were morphologically evaluated, IHC staining was done for FH, 2SC, CKIT, CK7, PAX8 and molecular studies were performed with TSO-500 for the evaluation of other genes. Clinicopathological correlation was done in all cases. Results: The tumors had been identified radiologically and were suspicious for malignancy. Age range was 37-73 years, and all the patients were female. Two patients had coexistent HLRCC cancers while two only had the oncocytomas. Localization was left kidney for all the masses, which were brown in color and well circumscribed and varied in size from 0.7 to 4 cm. In one patient, four separate masses were identified with different locations and sizes, but with the same morphology. This specific patient presented with two additional masses in the opposite kidney later. Tumors were composed of large oncocytic cells with prominent granular eosinophilic cytoplasm and dark pyknotic nuclei. No evidence of atypia, mitosis or necrosis was found. FH was positive, 2SC and CK7 were negative on IHC stains, whereas CKIT showed diffuse membranous positivity. Tumors were diagnosed as oncocytomas. All patients were positive for FH germ line mutation and the mutation was also identified in the tissues. Other molecular studies on the patient with multiple tumors showed additional pathogenic ERCC2 inactivating mutation, suggesting germline, which is rarely encountered in kidney tumors. All the patients are alive and free of disease up to 10 years after diagnosis. Conclusion: HLRCC cancers can have a variety of morphologic patterns and frequently have oncocytic features. Clinical information, genetic testing and special techniques are helpful in the diagnosis of these high-grade tumors. Recognizing that other benign indolent tumors with oncocytic features can occur in this syndrome is important to avoid errors in diagnosis and treatment. Citation Format: Dilara Akbulut, Mark Ball, Mark Raffeld, Marston Linehan, Maria J. Merino. Benign oncocytic tumors in the setting of HLRCC syndrome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1518.

A Rare Case of Cutaneous Granular Cell Tumor Misdiagnosed as Sebaceuos Cyst

Granular cell tumor (GCT) is a rare benign skin tumor. The tumor mostly presents with a symptomatic slowly growing solitary nodule and no overlying skin changes; therefore, it is not always considered in the differential diagnosis. We report a case of cutaneous GCT in the right supra-scapular region in a 43-year-old middle eastern female, who presented with a 2-year history of a slowly growing mass, with a dimension of 3 × 2 cm, initially misdiagnosed as a sebaceous cyst and later diagnosed as a GCT at the histopathological examination, followed by second excision with wide margins. The tumor cells had centrally located nuclei and granular eosinophilic cytoplasm and stained positively for S100 and CD68 antibodies on immunohistochemistry. Even though GCTs are rare, they should be thought of when diagnosing soft tissue tumors under the skin. Malignant changes have been reported in cases after long term follow-up, so surgical removal with wide margins is considered the best line of management.