Metastases to the parotid glands: An institutional experience.

BACKGROUND: Metastatic lesions to the salivary gland are rare and mostly affect the parotids. Metastases represent 8% of all malignant lesions of the parotid gland. Around 80% originate from squamous cell carcinomas (SCC) of the head and neck region. Fine needle aspiration (FNA) plays a crucial role in distinguishing primary salivary gland lesions from metastases. Herein we describe our series of metastases to the parotid glands. MATERIALS AND METHODS: We analysed 630 parotid gland FNAs over a decade including conventional and liquid-based cytology specimens. Ancillary techniques such as immunocytochemistry (ICC) were conducted on cell blocks. RESULTS: Eighty (12.4%) cases were malignant lesions, of which 53 (63.75%) were metastases including 24% melanoma, 22.6% SCC, 19% renal carcinomas, 7.5% breast carcinomas, 11.3% lung, 9% intestinal and 1.8% testicular, malignant solitary fibrous tumour and Merkel cell carcinoma. The 53 cases, classified according to the Milan system for salivary cytopathology, belonged to 5 Suspicious for malignancy (SFM) and 48 malignant (M) categories. Forty had a known history of primary malignancy (75.4%), while 13 were suspicious to be a metastatic localisation (24.5%), distributed as 5SFM (2SCC and 3Melanoma) and 8 M. A combination of clinical history, cytomorphology and ICC identified 100% of them. CONCLUSIONS: Fine needle aspiration plays a central role in the diagnostic workup of patients with metastatic lesions to their parotid glands, thereby defining the correct management. Diagnostic accuracy may be enhanced by applying ICC. Although melanoma and SCC are the most common histological types, several other malignancies may also metastasize to the parotid glands and should be kept into consideration.

Programmed Cell Death Ligand 1 Immunohistochemical Expression and Cutaneous Melanoma: A Controversial Relationship.

Cutaneous melanoma (CM) is traditionally considered one of the most "immunogenic" tumors, eliciting a high immune response. However, despite the presence of tumor-infiltrating lymphocytes (TILs), melanoma cells use strategies to suppress antitumor immunity and avoid being eliminated by immune surveillance. The PD-1 (programmed death-1)/PD-L1 (programmed death-ligand 1) axis is a well-known immune escape system adopted by neoplastic cells. Therefore, immunotherapy with PD-1 and PD-L1 inhibitors is quickly becoming the main treatment approach for metastatic melanoma patients. However, the clinical utility of PD-L1 expression assessment in CM is controversial, and the interpretation of PD-L1 scores in clinical practice is still a matter of debate. Nonetheless, the recent literature data show that by adopting specific PD-L1 assessment methods in melanoma samples, a correlation between the expression of such a biomarker and a positive response to PD-1-based immunotherapy can be seen. Our review aims to describe the state-of-the-art knowledge regarding the prognostic and predictive role of PD-L1 expression in CM while also referring to possible biological explanations for the variability in its expressions and related treatment responses.

Some uncommon cystic lesions in the anterior head and neck region: Pitfalls to be avoided on cytology.

Cystic lesions of the anterior head and neck region are a challenging and frequent finding on cytological smears. The scant amount of cellular material in cystic slides poses the greatest difficulty to interpretation, so that frequently they are diagnosed as inadequate or with minimal cellular component. Despite the majority of cystic lesions being benign, a minor portion consist of malignant cystic entities. In these latter cases, the evidence of very scant malignant cells can be misdiagnosed and/or underestimated, leading to a false negative diagnosis. Many papers have already described and detailed the range of possible benign and malignant cystic lesions in head and neck. In the current review we have focused on the less common entities that often lead to serious misinterpretation.

Bladder Epicheck Test: A Novel Tool to Support Urothelial Carcinoma Diagnosis in Urine Samples.

Bladder cancer and upper urothelial tract carcinoma are common diseases with a high risk of recurrence, thus necessitating follow-up after initial treatment. The management of non-muscle invasive bladder carcinoma (NMIBC) after transurethral resection involves surveillance, intravesical therapy, and cytology with cystoscopy. Urinary cytology, cystoscopy, and radiological evaluation of the upper urinary tract are recommended during follow-up in the international urological guidelines. Cystoscopy is the standard examination for the first assessment and follow-up of NMIBC, and urine cytology is a widely used urinary test with high sensitivity for high-grade urothelial carcinoma (HGUC) and carcinoma in situ (CIS). In recent years, various urinary assays, including DNA methylation markers, have been used to detect bladder tumors. Among these, the Bladder EpiCheck test is one of the most widely used and is based on analysis of the methylation profile of urothelial cells to detect bladder neoplasms. This review assesses the importance of methylation analysis and the Bladder EpiCheck test as urinary biomarkers for diagnosing urothelial carcinomas in patients in follow-up for NMIBC, helping cytology and cystoscopy in doubtful cases. A combined approach of cytology and methylation analysis is suggested not only to diagnose HGUC, but also to predict clinical and histological recurrences.

First-line ICIs in renal cell carcinoma.

Treatment of metastatic renal cell carcinoma (mRCC) has radically changed, switching from interferon alfa (IFN-α) and high-dose interleukin-2 (HD IL-2) to new targeted therapies directed against tumoral neoangiogenesis, the mammalian target of the rapamycin (mTOR) pathway and immune checkpoints. Of note, the inhibition of immune checkpoints restores antitumor immune response, therefore promoting immune-mediated elimination of neoplastic cells. The best example of this targeted treatment is represented by PD-1/PD-L1 inhibition that has become the standard of care in mRCC treatment and has improved mRCC patients' prognoses after failure of other targeted therapies. In this manuscript, we review the main therapeutic protocols adopted for mRCC, based on the use of immune checkpoint inhibitors (ICIs) alone or combined with other drugs.

Updates from Our Institutional Experience with Thyroid Nodules Diagnosed as Metastases.

BACKGROUND: Thyroid metastases (TMs) are a rare entity, ranging between 0 and 24% in the autopsy series. In the assessment of the best management, the discrimination between a primary and a metastatic thyroid lesion is crucial. In this regard, fine needle aspiration cytology (FNAC) is likely to play a crucial role especially when ancillary techniques (i.e., immunocytochemistry (ICC) and molecular testing) are carried out. METHODS: We searched for all the TMs diagnosed using FNAC and analyzed between 2014 and 2023. The cases were processed with liquid-based (LBC) and ICC and molecular testing performed on LBC-stored material. RESULTS: We reported 2.2% (19 cases) of TMs out of 1022 malignancies. TMs included: 1 larynx carcinoma (LX-Ca), 1 melanoma, 2 breast carcinomas (B-Ca), 3 lung carcinomas (LG-Ca), 4 gastro-intestinal carcinomas (GI-Ca), and 8 clear cell renal carcinomas (CCRC). All patients had a previous cancer history, between 300 and 2 months from the primary cancers. The morphological features were supported by ICC, which were contributive in 100% of cases. All TMs cases were characterized by multiple thyroid nodules except the melanoma case. Four cases underwent total thyroidectomy (1 B, 1 LX, 1 melanoma, and 1 CCRC) whilst 15 TMs were treated with radio-chemotherapy. CONCLUSIONS: FNAC empowered the diagnostic workup of patients with TMs avoiding useless surgery. The low sensitivity of cytology might be reinforced by the application of ancillary techniques. We found a predominant rate of kidney metastatic carcinomas, followed by lung and breast. TMs are frequently multifocal and in a context of a systemic disease so a tailored therapy seems to be the best treatment.

Diagnostic role of FNA cytology in the evaluation of cervical lymph nodes in thyroid cancers: Combined evaluation of thyroglobulin in eluate from FNA cytology.

BACKGROUND: The presurgical evaluation of cervical lymph nodes (CLNs) in the management of thyroid malignant lesions is crucial for the extent of surgery or detection of metastases. In these last decades, fine-needle aspiration cytology (FNAC) has been shown to have a central role in the detection of nodal thyroid metastases. It is adopted for the possibility of confirming suspected metastases either in the presurgical phase or in the follow-up of patients after thyroidectomy. However, FNAC from CLNs can be challenging, especially in cystic lesions. In this regard, the combination of FNAC with thyroglobulin measurement in the eluate from FNAC (Tg-FNAC) seems to increase the sensitivity of FNAC in the detection of CLN metastases. The role of FNAC and Tg-FNAC was investigated in this series. METHODS: One hundred fifty-three prospective cytological samples of CLNs were studied along with surgical follow-up in the period between 2020 and 2022. Immunocytochemistry (ICC) was performed on liquid-based cytology-stored material. RESULTS: One hundred fifty-nine enlarged CLNs included 19 central lymph nodes and 140 CLNs. Forty-two thyroidal CLN metastases and 117 reactive lymph nodes were found. Thirty-one CLN dissections were performed in patients with a previous diagnosis of thyroid carcinoma (mostly papillary thyroid carcinoma [PTC]), whereas 128 CLNs with a concomitant suspicious and/or malignant thyroid nodule were found. There was one false-positive case among all the malignant histologically confirmed cases, and two of 117 reactive CLNs (1.7%) had a diagnosis of metastatic PTC. Markedly high Tg-FNAC was found in all metastatic CLNs, including 11 cystic metastatic CLNs detected by Tg-FNAC with a negative FNAC. ICC (including Tg, CK-19, and LCA) recognized nine cases with low Tg-FNAC and scant suspicious thyrocytes. Tg-FNAC plus FNAC diagnosed 94.2% of malignancies. CONCLUSIONS: FNAC represents a valid method for the evaluation of CLNs, especially combined with ICC. Tg-FNAC is an additional method with a useful role in FNAC.

Cystic lesions in the salivary gland. Pitfalls to be avoided on cytology.

Cystic lesions of the salivary glands are very uncommon entities. However, on occasion, some neoplasms of the salivary glands show a cystic component, which may be predominant or only partially cystic. Basal cell adenoma, canalicular adenoma, oncocytoma, sebaceous adenoma, intraductal papilloma, epithelial-myoepithelial carcinoma, intraductal carcinoma, and secretory carcinoma are such cystic entities. Cystic degeneration and necrosis, which can develop within solid tumours, represent another possibility. The ability to recognise this type of lesion is a challenge in diagnostic cytology because hypocellular fluid is frequently recovered. Furthermore, evaluating all of the differential diagnoses for cystic lesions of the salivary glands is helpful in obtaining the correct diagnosis. Herein, we evaluate the various types of cystic lesions within the salivary glands.

p53 expression in cytology samples may represent a marker of early-stage cancer.

BACKGROUND: TP53 gene plays a major role in the negative control of cell proliferation and in the regulation of signaling cascades. TP53 mutation may have a relevant role in the malignant transformation of thyroid cells as well as thyroid tumor progression. TP53 mutation has been detected only in few well differentiated thyroid carcinomas and is absent in benign conditions. METHODS: A total of 162 prospective thyroid cytology and corresponding histological samples diagnosed from atypia of indeterminate significance (AUS) to malignant, were studied via immunocytochemistry for p53. Hence, 50 benign lesions (B) were used as negative control. Molecular analysis for p53 only was performed. RESULTS: The cytology resulted in 50 B, 48 AUS, 40 follicular neoplasms (FNs), 23 suspicious for malignancy (SFM), and 1 malignant (M) case. The authors reported 102 negative and 60 positive p53 cases. The 60 positive cases included 27 cases with weak and/or focal cytoplasmic positivity (+1) and 33 with cases moderate (2+) to strong (3+) cytoplasmic and/or nuclear expression. Overall, 71 cases had histology (2 B, 11 AUS, 37 FN, 20 SFM, and 1 M) including 61.7% benign and 38.2% malignant diagnoses. Only 16 of 71 (5 FN, 10 SFM, and 1 M) were p53-positive. Furthermore, 100% AUS and 86.5% FN cases were p53-negative, none of which had malignant histology. All p53-positive cases were associated with a larger nodule size, tall-cell variant subtype, multifocality, extra thyroidal infiltration, and nodal metastases. Noninvasive follicular thyroid neoplasm with papillary like nuclear features were negative for p53. Few discrepancies in p53 intensity were observed on histology; there were no differences with the molecular testing. CONCLUSIONS: p53 might be useful in discriminating thyroid follicular lesions. p53 is likely to be a useful diagnostic marker in recognizing indeterminate lesions that are well-differentiated thyroid cancers.

Biliary Atresia in an Infant Presenting With Kabuki Syndrome: An Autopsy Report and Review of the Literature.

Biliary atresia (BA) is an inflammatory obliterative cholangiopathy which is very common during neonatal and infancy period. We present an autopsy report of a BA in an infant suffering from a genetic syndrome.

Update regarding the role of PD-L1 in oncocytic thyroid lesions on cytological samples.

AIMS: Several papers have shown that programmed death-ligand 1 (PD-L1) expression is a relevant predictive biomarker in anti-PD-L1 cancer immunotherapy. While its role in several human cancers is correlated with poor prognosis and resistance to anticancer therapies, in thyroid cancers the role of PD-L1 remains questionable. Few articles have studied PD-L1 in thyroid fine-needle aspiration cytology (FNAC), demonstrating a possible correlation with papillary thyroid carcinoma. However, its role in oncocytic thyroid lesions remains controversial. We accordingly examine the performance of PD-L1 immunostaining in liquid based cytology (LBC) from oncocytic lesions. METHODS: From January 2019 to March 2021, 114 thyroid lesions diagnosed by FNAC from lesions with a predominant oncocytic component, were enrolled for evaluation by PD-L1 immunostaining on both LBC and corresponding histology samples. RESULTS: The FNAC cohort included 51 benign (B, negative controls), 4 atypia of undetermined significance/follicular lesions of undetermined significance (AUS/FLUS), 57 follicular lesions (follicular neoplasm/suspicious for FN, FN/SFN) and 2 suspicious for malignancy (SFM) cases. Fifty-four cases (11B, 2 AUS/FLUS, 39 FN/SFN and 2 SFM) had histological follow-up including: 1B case resulted as a hyperplastic oxyphilic nodule in Hashimoto thyroiditis (HT), 10B as goitre, 2 AUS/FLUS cases as oncocytic adenomas (OAs); 39 FN/SFN included 27 OAs, 4 FA and 8 oncocytic follicular carcinoma (OFC). The two SFM cases were diagnosed on histopathology as OAs. Increased plasma membrane and cytoplasmic PD-L1 expression were found in 47 cases of the LBC cases (41.2%). Among the histological series, 67.3% of OAs and 75% of OFC had PD-L1 expression, while negative PD-L1 was found in hyperplastic oncocytic cells in HT. A positivity in more than 30% of the neoplastic cells was found in 72.9% of the cases including six OFC. CONCLUSIONS: These data suggest that PD-L1 expression is expressed in oncocytic thyroid lesions. While weak PD-L1 expression failed to discriminate benign from malignant lesions, OFC demonstrated more intense cytoplasmic and membranous expression.

What psammoma bodies can represent in the thyroid. What we recently learnt from a story of lack of evidence.

The detection of psammoma bodies (PBs) in the thyroid gland is commonly associated to classic papillary thyroid carcinoma (PTC) and are frequently encountered in differnt subtypes of PTCs. Nonetheless, the evidence of PBs without a PTC may represent a diagnostic challenge. The general statement is that PBs represent a metastatic finding of PTC either when encountered inside the thyroid parenchyma or in the perithyroidal lymph nodes. The majority of authors assess that in presence of PBs, a search for an occult PTC is strongly encouraged and mandatory, especially if a lobectomy had been performed. In fact, it is not uncommon that a contralateral or ipsilateral tumor, mostly PTC, is found leading to the suggestion that the best recommendation is to submit the entire thyroid tissue. Nonetheless, when a cancer has not been found, the possibility of the rare evenience that PBs are likely to be associated with benign conditions should be considered among the differential diagnosis. Herein a short commentary and review of the literature on PBs detection and its diagnosis, based on our recent experience.

DOG1 as an Immunohistochemical Marker of Acinic Cell Carcinoma: A Systematic Review and Meta-Analysis.

DOG1 is a transmembrane protein originally discovered on gastrointestinal stromal tumors and works as a calcium-activated chloride channel protein. There are a limited number of articles on the potential utility of this antibody in the diagnosis of salivary gland tumors in routine practice. In this study, we aimed to investigate the role of DOG1 as an immunohistochemical marker in patients with salivary acinic cell carcinoma (ACC) through meta-analysis. A literature search was performed of the PubMed, Scopus, and Web of Science databases for English-language studies published from January 2010 to September 2021. The literature search revealed 148 articles, of which 20 were included in the study. The overall rate of DOG1 expression in salivary acinic cell carcinoma was 55% (95% CI = 0.43-0.58). Although ACC is a challenging diagnosis, paying careful attention to the cytomorphological features in conjunction with DOG1 immunostaining can help to reach an accurate diagnosis.

Approach to FNA of Thyroid Gland Cysts.

Fine needle aspiration is a well-known procedure for the diagnosis and management of thyroid lesions, representing the first diagnostic tool for the definition of their nature. In clinical practice, a thyroid nodule can be classified as solid, cystic, and partially cystic based on its internal components. Different thyroid imaging reporting systems and cytologic diagnostic systems have focused their attention on solid nodules, which are more frequently linked with a malignant outcome. In fact, numerous papers demonstrated that nodules with microcalcifications, a taller-than-wide shape, hypoechogeneity, and irregular margins, are more likely to be malignant on histology. Nevertheless, according to the literature, the risk of malignancy in a partially cystic thyroid nodule ranges between 3.3 and 17-5%, including, for instance, the possible diagnosis of a cystic papillary thyroid carcinoma and other malignant entities. Therefore, in the current review article, we are going to discuss the approach to thyroid cystic lesions on fine needle aspiration cytology.

A Novel Morphological Parameter Predicting Fibrotic Evolution in Myeloproliferative Neoplasms: New Evidence and Molecular Insights.

Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) represent a group of hematological disorders that are traditionally considered as indistinct slow progressing conditions; still, a subset of cases shows a rapid evolution towards myelofibrotic bone marrow failure. Specific abnormalities in the megakaryocyte lineage seem to play a central role in this evolution, especially in the bone marrow fibrosis but also in the induction of myeloproliferation. In this review, we analyze the current knowledge of prognostic factors of MPNs related to their evolution to myelofibrotic bone marrow failure. Moreover, we focused the role of the megakaryocytic lineage in the various stages of MPNs, with updated examples of MPNs in vitro and in vivo models and new therapeutic implications.

Molecular Characterization of Thyroid Follicular Lesions in the Era of "Next-Generation" Techniques.

It is unequivocally recognized that thyroid nodules are frequently detected in the adult population and mostly characterized by benign lesions (up to 70% of them), with only 5%-15% malignant lesions. The evaluation of thyroid lesions with fine-needle aspiration cytology (FNAC) represents one of the first and most useful diagnostic tools in the definition of their nature. Despite the fact that the majority of thyroid lesions are correctly diagnosed as either benign (70%-75%) or malignant (5%-10%) entities, the remaining nodules (20%-25%) represent the "gray zone" of follicular lesions, which belong to indeterminate categories, according to the different classification systems. This indeterminate group of lesions includes both benign and malignant entities, which cannot be easily discriminate with morphology alone. In these last decades, the increasing role of molecular testings, feasibly performed on cytological material combined with the discoveries of specific genetic alterations in the field of thyroid pathology, has opened the pace to their more accurate and specific contribution on cytology. In fact, in 2015, in the revised management guidelines for patients with thyroid nodules and well-differentiated thyroid cancers (WDTCs), the American Thyroid Association (ATA) confirmed the performance of molecular testing in thyroid indeterminate cytology, and the same performance was addressed in recent update of the management of thyroid nodules in the second edition of the Bethesda system for reporting thyroid cytopathology (TBSRTC). In the current review, we discuss the role of molecular tests for the different thyroid diagnostic categories of the Bethesda system for reporting thyroid cytopathology, mostly focusing our attention on the follicular and indeterminate lesions.

Does Locally Advanced Thyroid Cancer Have Different Features? Results from a Single Academic Center.

BACKGROUND: Despite the fact that the majority of thyroid cancers are indolent, 15% of patients with well-differentiated carcinoma including papillary thyroid carcinoma (PTC) present with locally advanced thyroid cancer (LATC) at diagnosis. The current study analyzes a cohort of patients with LATC focusing on their risk for local recurrence, distant metastases, and overall survival. MATERIALS AND METHODS: From January 2010 to December 2020, 65 patients with LATC were retrieved, including 42 cases with preoperative cytological samples. BRAFV600E and TERT mutations were performed on both cytology and histopathology specimens in this cohort. RESULTS: Among the 65 cases, 42 (65%) were women. The median age was 60.1 years. Histological diagnoses included 25 (38.4%) with classic PTC and 30 (46.1%) aggressive variants of PTC, mostly tall cell variant (17 cases, 26.1%). Multifocality was seen in 33 cases (50.8%). All patients had nodal metastases. The most common site of extrathyroidal extension was the recurrent laryngeal nerve (69.2%). Staging revealed 21 cases were stage I, none were stage II, 33 were stage III, and 7 were stage IVa and 4 stage IVb. No differences were found between well and poorly/undifferentiated thyroid cancers. CONCLUSION: These data suggest that locally advanced thyroid cancers, including variants of PTC, exhibit a more aggressive biological course and should accordingly be more assertively managed.

Prognostic predictors in recurrent adult granulosa cell tumors of the ovary: a systematic review and meta-analysis.

BACKGROUND: Ovarian adult granulosa cell tumours are low-grade malignant sex cord-stromal neoplasm with a low recurrence rate. Prognostic factors for recurrence include tumor stage, tumor rupture in Stage I neoplasms and the presence of residual tumors after surgery. However, in recurrent tumors, prognostic factors for overall survival (OS) are lacking. In the present paper, we conducted a systematic meta-analysis with the aim to assess prognostic factors for OS in patients with recurrent GCT. METHODS: Electronic databases were searched for all studies assessing prognostic factors in recurrent adult granulosa cell tumor of the ovary. Student T test, Fisher's exact test and Kaplan-Meier survival analysis with long-rank test were used to assess differences among groups; a p value < 0.05 was considered significant. RESULTS: Eleven studies analyzing 102 recurrent tumors were included in the systematic review. Tumor stage and localization of recurrent tumors were significantly associated with OS on Kaplan-Meier analysis; Cox regression analysis showed a HR of 0.879 for the stage II, of 3.052 for the stage III, and of 2.734 for stage IV tumor was significantly associated with OS (p = 0.037); observed HRs for abdominal and thoracic locations were of 2.405 and of 4.024, respectively. CONCLUSIONS: In conclusion, the present article emphasizes the prognostic significance of tumor stage > II and extrapelvic anatomic sites of recurrences in patients with recurrent granuolase cell tumors of the ovary.

Depth of Stromal Invasion as the Most Prognostically Relevant Regression System in Locally Advanced Cervical Cancer after Neoadjuvant Treatment: A Systematic Review and Meta-Analysis Grading.

Background: several different criteria have been proposed to categorize the pathological response in cervical cancer after neoadjuvant therapy; although it is unclear what the most prognostically valuable one is. Objective: to assess the prognostic value of pathological criteria for categorizing the response in cervical cancer after neoadjuvant therapy, through a systematic review and meta-analysis. Methods: four electronic databases were searched from January to December 2020 for all studies, assessing the prognostic value of pathological response in cervical cancer after neoadjuvant therapy. Hazard ratio (HR) for overall survival (OS) was calculated with a significant p-value < 0.05. A meta-analysis was performed for each criteria assessed in at least three studies. Results: sixteen studies were included. Criteria for pathological response included (i) residual stromal invasion < vs. >3 mm; (ii) complete response vs. any residual; (iii) proportion of viable cells; (iv) residual tumor diameter; and (v) intracervical vs. extracervical residual. Criteria (i) and (ii) were suitable for meta-analysis. The presence of a residual tumor with stromal invasion > 3 mm showed a HR of 4.604 (95% CI; 3.229-6.565; p < 0.001), while the presence of any residual showed a HR of 1.610 (95% CI; 1.245-2.081; p < 0.001); statistical heterogeneity was absent in both analyses. Conclusions: dichotomizing the pathological response in cervical cancer after neoadjuvant therapy as < vs. >3 mm stromal invasion is more prognostically valuable than dichotomizing as complete response vs. any residual. Further studies are necessary to evaluate other systems.

Fourier Transform Infrared Analysis of Urinary Calculi and Metabolic Studies in a Group of Sicilian Children.

INTRODUCTION: Prevalence of urinary calculi in children has been increasing in the past years. We performed an analysis of the chemical composition of stones formers of the pediatric population in our geographical area over the years 2005 to 2013. MATERIALS AND METHODS: Fourier transform infrared spectroscopy was employed for the determination of the calculus composition of a group of Sicilian children, and metabolic studies were performed to formulate the correct diagnosis and establish therapy. RESULTS: The prevalence of stone formation was much higher for boys than for girls, with a sex ratio of 1.9:1. The single most frequent component was found to be calcium oxalate monohydrate, and calcium oxalates (pure or mixed calculi) were the overall most frequent components. Calcium phosphates ranked 2nd for frequency, most often in mixed calculi, while urates ranked 3rd. The metabolic disorder most often associated with pure calcium oxalate monohydrate calculi was hypocitraturia, while hyperoxaluria was predominantly associated with calcium oxalate dihydrate calculi. CONCLUSIONS: Mixed calculi had the highest prevalence in our pediatric population. Our data showed that Fourier transform infrared spectroscopy was a useful tool for the determination of the calculi composition.