A previously undescribed variant of cutaneous clear-cell squamous cell carcinoma with psammomatous calcification and intratumoral giant cell granulomas.

Cutaneous clear-cell squamous cell carcinoma (ccSCC) is a rare variant of SCC composed of clear cells that lack cytoplasmic glycogen or evidence of tricholemmal keratinization. We report a previously undescribed variant of ccSCC with psammomatous calcification and intratumoral giant cell granulomas. The differential diagnosis with trichilemmal carcinoma is outlined according to the criteria of the fourth edition of World Health Organization (WHO) classification. Our findings outline that psammomatous calcification may occur inside the keratinous pearls of the neoplastic lobules triggering an intratumoral giant cell granulomatous reaction. The prognostic significance of this histopathological presentation is unknown but the potential for formation of psammoma bodies in cSCC should be considered to avoid diagnostic pitfalls.

Calcification and ossification in conventional schwannoma: A clinicopathologic study of 32 cases.

Calcification and ossification are uncommon in schwannomas; however, when present these findings may cause diagnostic confusion with other mesenchymal tumors which more frequently harbor these features. We sought to better characterize the type and rate of calcification and ossification in schwannomas. Cases of schwannoma diagnosed at our institution from 2005 to 2019 were reviewed to determine the type and amount of calcification and ossification present. Of 2116 total cases of schwannoma reported during the study period, 38 cases harbored calcification or ossification per the pathology report. Thirty-two of the 38 cases had slides available for review, of which 27 (84.3%) showed calcification, nine showed ossification (28.1%), and four (12.5%) cases demonstrated both. Foci of ossification typically occurred adjacent to large vessels. Of the 27 cases showing calcification, coarse dystrophic calcification was seen in 22 cases, psammomatous calcification in nine cases, and combined dystrophic and psammomatous calcification was seen in four cases. Cases with psammomatous calcification predominantly occurred in spinal roots and cerebellopontine angle of a younger age group with almost equal gender distribution. All four cases tested for protein kinase cyclic adenosine monophosphate-dependent type I regulatory subunit alpha immunohistochemical stain demonstrated retained expression. We confirm that calcification and ossification are rare findings in schwannoma. Awareness that these features may be present in these tumors will prevent misdiagnosis and ensure appropriate clinical management.

Thoracic psammomatous meningioma with osseous metaplasia: a controversial diagnosis of a case report and literature review.

BACKGROUND: Spinal psammomatous meningioma with calcification is commonly observed, but distinctive osseous differentiation rarely occurs. CASE PRESENTATION: Here, we described a 52-year-old female complaining of chronic back pain for 5 years. CT and MRI examinations revealed an intradural extramedullary mass at the T4 level. The tumor was meticulously excised en bloc. Under the microscope, the tumor was found to be composed of conspicuous calcified psammoma bodies with remarkable immature bone formation. A primary diagnosis of psammomatous meningioma was made based on the recent WHO classification of tumors of the CNS, whereas other pathologists focused on the osseous components and preferred metaplastic meningioma as the proper subtype. A literature review was conducted, and only five cases have been reported with the same histopathological condition. Experts finally reached a consensus based on the acknowledged notion of the preferential diagnosis of psammomatous meningioma, as well as the current evidence and popular opinion that ossification is generated from osteogenic differentiation of pluripotent cells rather than the accumulation of psammoma bodies. CONCLUSIONS: A final diagnosis of psammomatous meningioma with osseous metaplasia was made. The rigid and adherent features complicate total resection of the tumor and increase the risk of neurologic deficits.

Sporadic melanotic schwannoma with overlapping features of melanocytoma bearing a GNA11 mutation in an adolescent girl.

Melanotic schwannoma (MS) is a soft tissue neoplasm that shares histologic features with melanocytic tumors and schwannomas. A type of MS, called psammomatous MS (PMS), is associated with Carney complex (CNC), which is caused by PRKAR1A mutations. Other pigmented neoplasms, such as uveal melanomas and melanocytomas (MCs), are associated with genetic defects in other genes including GNA11. We report an adolescent female with a large sporadic mesenteric MS with complex histologic findings reminiscent of both PMS and MC. The lesion carried a mutation of the GNA11 gene. We conclude that sporadic MSs may occur rarely in adolescents without CNC; MSs may also be associated with somatic GNA11 mutations.

Imaging features of intracranial psammomatous meningioma.

PURPOSE: This study was conducted to describe the imaging features of intracranial psammomatous meningioma (IPM). MATERIALS AND METHODS: Twenty-three patients with a histopathological diagnosis of IPM between January 2007 and August 2016 were retrospectively reviewed. Twenty-two patients underwent contrast-enhanced MRI scanning, and 16 underwent non-enhanced CT. RESULTS: A total of 23 adult patients (3 men, 20 women; mean age, 55.3±7.0 years) with 30 IPMs, including 3 patients with multiple IPMs, were recruited. Twenty tumours (66.7%) were located at the cerebral convexity. The mean size of the lesions was 2.42±0.92cm (range, 1.2-4.8cm). All tumours had a regular shape. On CT scans, 13 masses (13/22) were totally replaced with calcifications, and calcifications were observed in 21 cases (21/22) with higher density. There were 22 cases (22/30) of IPMs presenting adjacent hyperostosis, while 8 cases (8/30) presented no skull changes that were not close to the skull. Nearly half of the cases (14/29) showed mixed hypo- and hyperintensity on T2-weighted images and DWI. PTBE was present in 8 tumours and absent in the other 22, among which only 4 tumours were accompanied by severe oedema. CONCLUSIONS: These radiological findings may facilitate correct diagnosis for IPMs and thus presurgical planning, prognosis evaluation and treatment of meningiomas.

Melanotic schwannoma: an 11-year case series.

Melanotic or melanocytic schwannoma is a rare tumour usually involving spinal nerve roots but can also present at other anatomical locations. Although there are less than 200 cases reported, melanotic schwannomas can have distinctive imaging features but there is limited recent literature on its often characteristic radiological appearances. Recent publication of the largest case series thus far has suggested melanotic schwannoma to be a separate entity to other schwannomata and that its reclassification to a malignant lesion be under consideration. We present a case series over an 11-year period to highlight salient imaging features with reference to the current concerns regarding its malignant potential.

The clinicopathologic significance of psammoma bodies in cytology specimens: A series of 78 cases.

BACKGROUND: Currently the clinicopathologic significance of psammoma bodies in cytology specimens are not completely understood, including types of cytology specimens and pathologic conditions frequently associated with this unique cytologic feature. In this study, we undertook a retrospective approach to review the specimen types, cytology preparations, patient characteristics, organs or tissues involved and differential diagnoses in cytology specimens with the finding of psammoma bodies. METHODS: Cytology cases with the finding of psammoma bodies from January 2004 to December 2022 were retrieved from our institution's pathology databases, and their clinicopathological features were reviewed. RESULTS: A total of 78 cytology specimens with the finding of psammoma bodies were recorded in our CoPath system. The mean age at diagnosis was 59 years. The patient group showed female gender predominancy (90%). FNA specimens comprised about 38.5% of total cases. Other common specimen types were body cavity fluids (38.5%), including pleural effusion and peritoneal fluid, and about 20.5% of the cases were pelvic washing performed during gynecologic surgeries. Most cytology cases with psammoma bodies had a malignant diagnosis (69%). About 18% of the cases were in the indeterminate diagnostic categories, with 12% suspicious for malignancy and 6% of the cases with atypical cells. About 5% of cases were placed in the neoplastic category, while 8% of cases were negative for malignancy. About 79% of peritoneal cytology with psammoma bodies were neoplastic and mostly gynecologic tumors. Pleural fluids with psammoma bodies were very likely to be malignant and involved by serous carcinoma (15 of 16 cases, 94%). Papillary thyroid carcinoma was the second most common malignancy in our series, present in about 53% of thyroid cytologies with the finding of psammoma bodies. CONCLUSION: Our study showed that psammoma bodies in cytology preparations were more often associated with malignancies in our study of 78 cytology specimens (69%). The most sampled location in our study was peritoneal cavity, followed by pleural cavity, thyroid, lymph nodes, neck masses, and omentum. The clinicopathologic value of psammoma bodies in predicting malignancy varies depending on locations and specimen types.

Association of frequent NF2 mutations with spinal location predominance and worse outcomes in psammomatous meningiomas.

OBJECTIVE: Psammomatous meningiomas (PMs) are a rare histological subtype of meningioma but are rather frequent in spinal meningiomas. The authors aimed to analyze the incidence, clinical features, molecular alterations, long-term outcomes, and prognostic factors of PMs. METHODS: In total, 151 patients with PMs were included in this study. Clinical characteristics, molecular alterations, and progression-free survival (PFS) were analyzed in PMs. Clinical characteristics were compared between PMs and other WHO grade 1 meningiomas. Targeted sequencing of meningioma-relevant genes was performed to determine the molecular alterations in PMs. RESULTS: PMs accounted for 1.34% of all meningiomas. Clinically, spinal location (p < 0.001) and female predominance (p < 0.001) were statistically significant in PMs when compared with the other grade 1 subtypes. Radiologically, calcification was frequently found in PMs (88.24%). Genetically, NF2 was the most frequently mutated gene in PMs (59.7%), followed by TRAF7 and AKT1. Ten patients experienced recurrence during the long-term follow-up. Multivariate analysis demonstrated that age (p = 0.009), extent of resection (p < 0.001), Ki-67 index (p = 0.007), and NF2 status (p < 0.001) were independent prognostic factors in the cohort of PMs. Interestingly, NF2 mutation was detected in all (48/48) spinal PMs (SPMs) but in only 38.46% (35/91) of cranial PMs (CPMs), revealing a significant difference (p < 0.001). The mean Ki-67 index (p = 0.044) and proportion of PMs with PR-positive expression (p = 0.048) were significantly higher in SPMs than in CPMs. The frequent NF2 mutations are associated with spinal location predominance and worse PFS in PMs. CONCLUSIONS: Female sex and spinal location predominance were statistically significant in PMs. NF2 mutation was an independent predictor for worse PFS of PMs. Of note, NF2 mutation was detected in all SPMs but in only 38.46% of CPMs, revealing a significant difference.

Next-Generation DNA Sequencing of Grade 1 Meningioma Tumours: A Case Report of Angiomatous and Psammomatous Meningiomas.

We performed the next-generation sequencing (NGS) analysis of a rare grade 1 brain meningioma (angiomatous type) and a common grade 1 spinal meningioma (psammomatous type) and compared their mutation profiling. The data were analysed using the Ion Reporter 5.16 programme (Thermo Fisher Scientific, Waltham, MA). Sequencing analysis identified 10 novel variants and two previously reported variants that were common between these two tumours. Nine variants were missense, which included an insertion in EGFR c.1819_1820insCA, causing frameshifting, and a single nucleotide deletion in HRAS and HNF1A genes, causing frameshifting in these genes. These were common variants identified for both tumours. Also, 10 synonymous variants and 10 intronic variants were common between these two tumours. In intronic variants, two were splice site_5' variants (acceptor site variants). Typical of the angiomatous type tumour, there were 11 novel and six previously reported variants that were not found in the psammomatous tumour; three variants were synonymous, 11 were missense mutations, and three were deletions causing frameshifting. The deletion variants were in the SMARCB1, CDH1, and KDR genes. In contrast, eight novel and five previously reported variants were found in the psammomatous meningioma tumour. In this tumour, two variants were synonymous: a deletion causing a frameshifting in [(c.3920delT; p. (Ile1307fs)], and a two-base pair insertion and deletion (INDEL) [(c.3986_3987delACinsGT; p. (His1329Arg)] both in the APC gene were also found. Among our findings, we have identified that ALK, VHL, CTNNB1, EGFR, ERBB4, PDGFRA, KDR, SMO, ABL1, HRAS, ATM, HNF1A, FLT3, and RB1 mutations are common for psammomatous meningioma and angiomatous tumours. Variants typical for angiomatous (brain) meningioma are PIK3CA, KIT, PTPN11, CDH1, SMAD4, and SMARCB1; the variants typical for psammomatous meningioma are APC, FGFR2, HNF1A, STK11, and JAK3. The RET splice variant (c.1880-2A>C) found in both meningioma tumours is reported (rs193922699) as likely pathogenic in the Single Nucleotide Polymorphism Database (dbSNP). All missense variants detected in these two meningiomas are found in the cancer-driver genes. The eight variants we found in genes such as EGFR, PDGFRA, SMO, FLT3, PIK3CA, PTPN11, CDH1, and RB1 are glioma-driver genes. We did not find any mutations in genes such as BRAF, IDH1, CDKN2A, PTEN, and TP53, which are also listed as cancer-driver genes in gliomas. Mutation profiling utilising NGS technology in meningiomas could help in the accurate diagnosis and classification of these tumours and also in developing more effective treatments.

Pulmonary Calcifying Fibrous Tumor in a Pediatric Patient: A Case Report.

A calcifying fibrous tumor (CFT), also known as calcifying fibrous pseudotumor, is an uncommon non-cancerous neoplasm usually located in the gastrointestinal tract. Its location in the lung is extremely rare, and only a few case reports have been published. This case report describes our diagnostic approach in a 9-year-old male patient with an incidental pulmonary mass. The mass was initially misdiagnosed, requiring multiple imaging tests and interventions to obtain the definitive diagnosis of pulmonary CFT. This paper aims to contribute to the limited information available on pulmonary CFT by presenting detailed findings from computed tomography and magnetic resonance imaging.

Sporadic spinal psammomatous malignant melanotic nerve sheath tumor: A case report and literature review.

Background: Sporadic Spinal Psammomatous Malignant Melanotic Nerve Sheath Tumor (SSP-MMNST) is a rare subgroup of peripheral nerve sheath tumors arising along the spine. Only a few reports of SSP-MMNST have been described. In this paper, we review the literature on SSP-MMNST focusing on clinical, and diagnostic features, as well as investigating possible pathogenetic mechanisms to better implement therapeutic strategies. We also report an illustrative case of a young female presenting with cervicobrachial pain due to two SSP-MMNSTs arising from C5-6 right spinal roots. Case description: We report a case of a 28-year-old woman presenting with right arm weakness and dysesthesia. Clinical examination and neuroimaging were performed, and, following surgical removal of both lesions, a histological diagnosis of SSP-MMNST was obtained. Results: The literature review identified 21 eligible studies assessing 23 patients with SSP-MMNST, with a mean onset age of 41 years and a slight male gender preference. The lumbar district was the most involved spinal segment. Gross-total resection (GTR) was the treatment of choice in all amenable cases, followed in selected cases with residual tumor by adjuvant radiotherapy or chemotherapy. The metastatic and recurrence rates were 31.58% and 36.8%, respectively. Conclusion: Differently from common schwannomas, MMNST represents a rare disease with known recurrence and metastatization propensity. As reported in our review, SSP-MMNST has a greater recurrence rate when compared to other forms of spinal MMNST, raising questions about the greater aggressiveness of the former. We also found that residual disease is related to a higher risk of systemic disease spreading. This metastatic potential, usually associated with primary lumbar localization, is characterized by a slight male prevalence. Indeed, whenever GTR is unachievable, considering the higher recurrence rate, adjuvant radiation therapy should be taken into consideration.

The emerging role of NF2 alterations in new and established subtypes of renal cell carcinoma.

Genomic alterations are increasingly important in the current paradigms for the classification, diagnosis, and treatment of renal cell carcinoma. Biallelic alterations involving NF2 have been identified across several currently recognized subtypes of renal cell carcinoma including clear cell renal cell carcinoma and papillary renal cell carcinoma among others and may be associated with a more aggressive disease course as well as advanced stage at presentation. In addition, emerging evidence suggests the existence of a clinicopathologically distinct subset of renal cell carcinoma cases driven by biallelic loss of NF2 expression. This subset of tumors is morphologically characterized by a constellation of morphologic features including hyalinizing fibrosis, eosinophilic cytology, psammomatous calcifications, and a nested growth pattern. These tumors include the recently described entities of biphasic hyalinizing psammomatous renal cell carcinoma as well as renal cell tumor with sex cord/gonadoblastoma-like features. Despite their oftentimes aggressive behavior, there is some evidence that these tumors may respond favorably to treatment regimens incorporating immune checkpoint inhibitors.

Malignant psammomatous melanotic schwannoma mimicking adrenal cyst: case report.

Background: Melanotic schwannoma is a melanin producing nerve sheath tumors. Rarely, it can be associated with psammoma bodies, called psammomatous melanotic schwannoma. Psammomatous melanotic schwannomas are associated in up to 10% of the cases with Carney's syndrome. The rarity of the lesion, which may present at different localizations create difficulty in placing a correct initial diagnosis. Definitive diagnosis is made after complete tumor excision and pathomorphological evaluation. The prognosis depends on the anatomical localization, local invasion and presence of a high mitotic index. The main pathomorphological differential diagnosis includes schwannomas and other melanin producing tumors as melanoma. Case presentation: We present a case of an 11-year-old female with cystic lesion adjacent to right adrenal gland, mimicking adrenal cyst. Ultrasound guided biopsy was undertaken due to the cystic appearance of the formation and the lack of certain diagnosis from the non-invasive diagnostic tests. No signs of cellular and nuclear atypism were observed. The diagnosis of benign endothelial cyst with spontaneous hemorrhage was suggested. The patient underwent transabdominal laparoscopic adrenalectomy en-bloc with the cyst to prevent spillage of the cyst content due to the intimate adhesion of the lesion to the adrenal gland and vena cava inferior. Pathomorphological examination revealed malignant psammomatous melanotic schwannoma. The adrenal gland was intact with no tumor infiltration. The patient was followed up on the 1st and 2nd month afterwards the surgery by MRI with no signs of local recurrence and postoperative complications. Conclusion: Psammomatous melanotic schwannoma near adrenal gland are rare and present difficulty with exact preoperative diagnosis. Complete resection should always be provided. Laparoscopic surgery is feasible if radical excision is not compromised. Long-term follow-up and Carney's syndrome surveillance after complete excision are recommended especially in young patients.

Case Report: Incidental discovery of primary peritoneal psammocarcinoma.

Psammocarcinoma is an uncommon subtype of low-grade serous carcinoma. It is characterized by the presence of extensive psammoma bodies and can have either an ovarian or peritoneal origin. To our knowledge fewer than 30 cases of primary peritoneal psammocarcinoma (PPP) have been reported in the English literature. We report a rare case of  PPP in a 74-year-old female, discovered fortuitously within a laparotomy for gallbladder lithiasis. At laparotomy, multiple nodular implants involving the omentum, the peritoneum and a magma of intestinal loops in the right iliac fossa were noted. A biopsy from nodules was performed. Gross examination showed multiple nodules of different sizes in the fat tissue. Pathologic examination showed massive psammoma bodies representing more than 75% of the tumor. The final diagnosis was psammocarcinoma. Our patient was referred to the gynecologic department for further investigation and to ascertain whether the tumor arose from the ovaries or peritoneum. Hysterectomy, bilateral adnexectomy and omentectomy were performed. Macroscopic examination showed that both ovaries were intact having a normal size. No invasion of ovarian stroma was shown in microscopic examination. The patient died of SARS-CoV-2 (COVID-19) six days after the surgery. PPP is a rare type of  low-grade serous carcinoma. The behavior of this tumor is unclear, and the treatment is not standardized because of its rarity and lack of long-term follow-up. More cases need to be studied for better understanding and improvement of the management protocols.

Renal cell tumor with sex-cord/gonadoblastoma-like features: analysis of 6 cases.

Renal tumors are one of the most diverse groups of tumors in pathology. Many emerging and important entities have been described recently. Here, we describe a series of renal tumors occurring in adult patients, with distinct histologic features, and with a striking resemblance to gonadal sex cord-stromal tumors. Patients were three males and three females aged 39-82 years; tumor size ranged from 0.9 to 3.6 cm. Five tumors were organ-confined, while one case had a focal perinephric invasion. No aggressive behavior was noted. Microscopically, all the tumors were composed of loose or compact tubular structures with elongated or angulated shapes. The tumor cells were cylindrical or cuboidal, with pale eosinophilic cytoplasm, irregular nuclear membranes, and ISUP/WHO grade 2-3 nuclei. The stroma showed focal or prominent collagen deposition with prominent basement membrane-like material. In all cases, the tumor cells were positive for PAX8, CD10, and vimentin and retained positivity for FH and SDHB. Cathepsin K and AMACR were variably positive. Tumors were negative for HMB45, Melan A, TFE3, SF1, inhibin, calretinin, ER, PR, CD117, OCT3/4, SALL4, ALK, and WT1. Molecular studies showed no abnormalities in TFEB, TFE3, or FH genes. In 3/4 tested cases, mutation of the NF2 gene was present. In all the tested male cases, loss of the Y chromosome was found. In the relatively short follow-up, these tumors appear to have indolent behavior. This study expands the clinicopathologic diversity of renal cell tumors by describing a series of potentially novel tumors morphologically resembling gonadal sex-stromal tumors, with negativity for sex cord-stromal markers. Potential relationship to recently described biphasic hyalinizing psammomatous renal cell carcinoma is discussed.

Malignant melanotic nerve sheath tumor with PRKAR1A, KMT2C, and GNAQ mutations.

Malignant melanotic nerve sheath tumor (MMNST) is a rare and potentially aggressive lesion defined in the 2021 WHO Classification of Tumors of the Central Nervous System. MMNST demonstrate overlapping histologic and clinical features of schwannoma and melanoma. MMNST often harbor PRKAR1A mutations, especially within the Carney Complex. We present a case of aggressive MMNST of the sacral region in a 48-year-old woman. The tumor contained PRKAR1A frameshift pR352Hfs*89, KMT2C splice site c.7443-1G>T and GNAQ p.R183L missense mutations, as well as BRAF and MYC gains. Genomic DNA methylation analysis using the Illumina 850K EpicBead chip revealed that the lesion did not match an established methylation class; however, uniform manifold approximation and projection (UMAP) placed the tumor very near schwannomas. The tumor expressed PD-L1, and the patient was treated with radiation and immune checkpoint inhibitors following en bloc resection. Although she had symptomatic improvement, she suffered early disease progression with local recurrence, and distant metastases, and died 18 months after resection. It has been suggested that the presence of GNAQ mutations can differentiate leptomeningeal melanocytic neoplasms and uveal melanoma from MMNST. This case and others demonstrate that GNAQ mutations may exist in malignant nerve sheath tumors; that GNAQ and PRKAR1A mutations are not always mutually exclusive and that neither can be used to differentiate MMNST or MPNST from all melanocytic lesions.

Psammomatous melanotic schwannoma - a rare neck lump.

This case report discusses a cervical psammomatous melanotic schwannoma - a rare form of peripheral nerve sheath tumour - which may be highly vascular and is often associated with the Carney complex. Significant intraneural bleeding, which was encountered intraoperatively, was controlled successfully with a gelatine-based thrombin haemostatic agent (Floseal®, Baxter International, Deerfield, IL, USA) without complication.

Biphasic Hyalinizing Psammomatous Renal Cell Carcinoma: Another Provisional Entity Emerging From the Papillary Renal Cell Carcinoma Pandora's Box.

Papillary renal cell carcinoma (especially type 2) is a Pandora's box with many newly described renal cell carcinomas emerging from it as a result of enhanced molecular techniques. Biphasic hyalinizing psammomatous renal cell carcinoma (BHPRCC) is the latest addition, which was first described a few months ago. Here, we report a case of BHPRCC to supplement the very limited literature available about this entity, and to highlight the characteristic morphology as well as the recurring molecular alterations in the neurofibromatosis 2 gene.

Heterotopic ossification in psammomatous spinal meningioma: a diagnostic controversy.

Heterotopic ossification (HO), a synonym for osseous metaplasia, is a pathological phenomenon, characterized by abnormal bone formation outside the skeletal system observed commonly in various neoplastic and non-neoplastic diseases. HO occurring in meningioma is exceptionally rare. We reportherein an unusual case of spinal meningioma containing numerous calcified psammoma bodies and extensive HO in a 75-year-old woman, who presented with progressive worsening bilateral lower limb weakness and numbness. The presence of remarkable bone formation within a meningioma is controversial among pathologists; while some regard them as psammomatous meningioma as the primary diagnosis, others prefer osteoblastic meningioma, a form of metaplastic meningioma. There is compelling molecular data to advocate that HO is an active disease process involving metaplastic (osseous) differentiation of meningioma stroma mesenchymal stem-like cells, but not the meningothelial-derived tumor cells. Henceforth, the term "metaplastic meningioma" may not be appropriate in this context. A plausible designation as "psammomatous meningioma with osseous metaplasia" defines this entity more accurately. This paper highlights the need for a unifying nomenclature to reduce diagnostic controversy caused by conflicting terms in the literature. The possible pathogenesis of this intriguing phenomenon is discussed.

The Morphological Spectrum of Papillary Renal Cell Carcinoma and Prevalence of Provisional/Emerging Renal Tumor Entities with Papillary Growth.

Renal cell carcinoma (RCC) represents a heterogeneous disease, encompassing an increasing number of tumor subtypes. Post-2016, the World Health Organization (WHO) classification recognized that the spectrum of papillary renal cell carcinoma is evolving and has long surpassed the dichotomic simplistic "type 1 versus type 2" classification. The differential diagnosis of pRCC includes several new provisional/emerging entities with papillary growth. Type 2 tumors have been cleared out of several confounding entities, now regarded as independent tumors with specific clinical and molecular backgrounds. In this work we describe the prevalence and characteristics of emerging papillary tumor entities in two renal tumor cohorts (one consisting of consecutive papillary tumors from a single institute, the other consisting of consultation cases from several centers). After a review of 154 consecutive pRCC cases, 58% remained type 1 pRCC, and 34% type 2 pRCC. Papillary renal neoplasm with reversed polarity (1.3%), biphasic hyalinizing psammomatous RCC (1.3%), and biphasic squamoid/alveolar RCC (4.5%) were rare. Among 281 consultation cases, 121 (43%) tumors had a dominant papillary growth (most frequently MiT family translocation RCCs, mucinous tubular and spindle cell carcinoma and clear cell papillary RCC). Our data confirm that the spectrum of RCCs with papillary growth represents a major diagnostical challenge, frequently requiring a second expert opinion. Papillary renal neoplasm with reversed polarity, biphasic hyalinizing psammomatous RCC, and biphasic squamoid/alveolar RCC are rarely sent out for a second opinion, but correct classification and knowledge of these variants will improve our understanding of the clinical behavior of renal tumors with papillary growth.