Diagnosis Of Clear Cell Sarcoma Research Articles

Clear cell sarcoma metastasizing to the pancreas

In this editorial based on a case report, we delve into a seldom-seen occurrence of clear cell sarcoma featuring pancreatic metastasis in a 47-year-old male patient. Recognized for its typical tendency to metastasize to the lungs, bones, and brain, clear cell sarcoma rarely extends its reach to the pancreas. Despite the initial absence of discernible abnormalities during the patient's physical examination, the manifestation of abdominal pain prompted further investigation. Subsequent abdominal computed tomography brought to light the presence of a pancreatic tumor, culminating in the definitive diagnosis of clear cell sarcoma with pancreatic metastasis. The successful management of this atypical presentation involved a series of surgical interventions, including distal pancreatectomy and splenectomy. This report not only sheds light on the infrequent manifestation of clear cell sarcoma within the pancreas but also underscores the pivotal role of vigilant postoperative follow-up in addressing this rare sarcoma. The emphasis on postoperative care serves as a crucial aspect of the broader narrative, acknowledging the need for ongoing monitoring and management to ensure a comprehensive and successful treatment trajectory for patients with this unique presentation of clear cell sarcoma.

Melanin-targeted [18F]-PFPN PET imaging may shed light for clear cell sarcoma.

Intracytoplasmic melanin pigment is a characteristic of clear cell sarcoma (CCS), which is a particularly deadly type of soft-tissue sarcoma. [18F]-N-(2-(diethylamino)ethyl)-5-(2-(2-(2-fluoroethoxy)ethoxy)ethoxy)picolinamide ([18F]-PFPN) is a positron emission tomography (PET) probe characterized by high melanin affinity. Therefore, this study aimed to investigate the feasibility of melanin-targeted [18F]-PFPN PET in patients with CCS. This prospective single-centre study recruited patients with pathologically confirmed CCS. [18F]-FDG PET/computed tomography and [18F]-PFPN PET/magnetic resonance imaging scans were performed within 1week of each other. The lesion numbers and [18F]-FDG and [18F]-PFPN PET parameters (maximum standardized uptake value [SUVmax], mean standardized uptake value [SUVmean], metabolic/melanotic tumour volume [MTV/MLTV], and total lesion glycolysis/melanin [TLG/TLM]) were collected. Three patients with CCS were recruited and received PET imaging. A total of 56 lesions were detected on [18F]-PFPN PET, including primary tumour and distant metastases. Identical lesions were not detected on [18F]-PFPN and [18F]-FDG PET. Twelve lesions (12/39, 30.77%) on [18F]-FDG imaging were missed on [18F]-PFPN, and 20 lesions (20/47,42.55%) on [18F]-PFPN imaging were missed on [18F]-FDG. In quantitative analysis, the [18F]-FDG SUVmean (4.60 ± 3.24) was higher than the [18F]-PFPN SUVmean (3.0 ± 2.63) in all lesions (P = 0.01). No significant correlations were found between the SUVmax, SUVmean, MLTV/MTV, and TLM/TLG values of [18F]-PFPN and [18F]-FDG (P > 0.05). Melanin-targeted [18F]-PFPN PET imaging is feasible for the diagnosis of CCS. Different imaging features were displayed on [18F]-PFPN and [18F]-FDG PET imaging, demonstrating the complementary role of the tracers. Combined use of the two imaging modalities would be preferred in patients with CCS. NCT05963035.

Clear cell sarcoma of soft tissue arising in the supraclavicular region: A cytological diagnosis

Clear cell sarcoma of soft tissue is a rare malignant neoplasm which constitutes about 1% of soft tissue tumors. It most commonly arises in the distal extremities of young adults. Peak incidence is in the third decade. More commonly seen in women than men. A 30 year old female presented with swelling in right supraclavicular region associated with pain since 3 months. CT scan findings revealed irregular and non-enhancing, hypodense lesion measuring 2.5x2x1cm in right supraclavicular region. Cytological features revealed abundant cellularity comprising of atypical cells mainly dispersed singly and arranged in loose cohesive groups. The cytoplasm was abundant, vacuolated at places, pleomorphic round to oval nucleus, placed centrally to eccentrically with prominent nucleoli. Diagnosis of malignant mesenchymal neoplasm was made on the basis of the cytomorphological details. Clear cell sarcoma was included in the differential diagnosis. Cytomorphological diagnosis was confirmed by histological and immunohistochemical diagnosis. When cytology of a soft tissue tumor shows high cellularity alongwith dispersion and loosely cohesiveness of cells, nuclear pleomorphism and conspicuous nucleoli, diagnosis of clear cell sarcoma may be considered.

Clear Cell Sarcoma of Soft Tissue: A Case Report

Introduction: Clear cell sarcoma (CCS), is an extremely rare type of sarcoma, frequently diagnosed in young adults, typically arises in the extremities of the limbs and has a predilection for occurring in the tendons and aponeuroses. In the past CCS was called malignant melanoma of the soft parts because the tumor shares clinical, histological and immunohistochemical similarities with amelanotic melanoma, but it is a unique lesion, distinct from melanoma. Case Report: A 33-year old woman with no significant history was referred with an unpainful bulky ulcerated tumor of the right ankle, appeared 05 years prior to presentation following a minimal trauma. The CT of the ankle revealed a bulky mass of the medial surface locally infiltrative associated to nodules of the surrounding adipose tissues and a unilamellar periosteal reaction without bone lysis or osteocondensation. MRI of the ankle showing a lobulated mass arising in the deep structures in iso-intense signal relative to adjacent muscle on T1 and heterogeneous high-signal intensity on T2 infiltrating surrounding adipose tissues without infiltration of muscles. Histological examination showed dermo-hypodermic malignant tumor proliferation. Round cells were arranged in nests separated by dense collagenous septa, with an abundant eosinophilic to clear cytoplasm. The immunohistochemical supplement were positive for Melan-A and HMB-45. Cytokeratin, Vimentin, Desmin and CD99 were negative. The extension assessment made of a head-chest-abdominal-pelvic CT scan showed multiple homolateral inguinal lymphadenopathies necrotic. No other metastasis was detected. The anatomo-clinical confrontation allowed to retain the diagnosis of CCS. Discussion: The tumor occurs most often in adolescents and young adults and was slightly more common in female than in male patients, CCS typically arises in the extremities of the limbs, its occurrence in the upper limbs is less common, described as a slowly growing mass painless. ..........

Whole‐exome sequencing in clear cell sarcoma of soft tissue uncovers novel prognostic categorization and drug targets

Whole‐exome sequencing in clear cell sarcoma of soft tissue uncovers novel prognostic categorization and drug targets

Xanthogranulomatous pyelonephritis in an eight year old male child: A case report and review of the literature.

Introduction and importanceXanthogranulomatous pyelonephritis is an extremely rare but known form of chronic pyelonephritis resulting from prolonged suppuration of the kidney. Pre-operatively, it may mimic renal tuberculosis or neoplastic lesions including renal cell carcinoma due to its vague clinical presentation, equivocal laboratory and radiological investigations. Due to its rarity and academic interest, herein we report such a rare case we recently encountered in our clinical practice.Case presentationAn-eight-year old male child patient resented to our hospital with three months history of abdominal distension associated with progressive left flank pain. Preoperative investigations including CT-scan were suggestive of nephroblastoma with differential diagnosis of clear cell sarcoma. Radical nephrectomy was performed and histopathology of the specimen confirmed the diagnosis of Xanthogranulomatous pyelonephritis. The patient fared well postoperatively and he had no symptoms in the subsequent follow up visits.Clinical discussionXanthogranulomatous pyelonephritis is a rare, severe and atypical form of chronic pyelonephritis due to infection (E. coli, Proteus) or stones. The disease may resemble renal cell carcinoma preoperatively. Thus, high index of suspicion is necessary for preoperative diagnosis.ConclusionPreoperative diagnosis of Xanthogranulomatous pyelonephritis may be a daunting task related to the rarity of its presentation. Thus, scrupulous histopathological evaluation is essential for the definitive diagnosis. Radical nephrectomy is the mainstay treatment of choice especially in diffuse cases.

Superficial Clear Cell Sarcoma (Melanoma of Soft Parts) of the Large toe in an 80-Year-Old Female With a Rare Cytogenetic Translocation

We present a case of clear cell sarcoma (CCS) on the left large toe of an 80-year-old female. CCS, also known as “melanoma of soft parts,” is a rare soft tissue neoplasm that exhibits melanocytic differentiation. Most cases occur on the distal extremities of young female adults. CCS shares histopathologic and immunohistochemical features with malignant melanoma that cause diagnostic difficulties distinguishing between these entities; therefore, cytogenetic studies of specific translocations are paramount in obtaining the correct diagnosis. The majority of CCS cases reveal a t(12;22)(q13;q12) EWSR1/ATF1 translocation, while a rare subset of CCS demonstrate a t(2;22) (q32:q12) EWS/CREB1 translocation. Our patient presented with a 50-year history of a nodule on the dorsum of her left large toe, with increasing size and tenderness over the past nine months. Histopathology and immunoperoxidase staining indicated CCS as a differential diagnosis. Cytogenetic analysis revealed a translocation in t(2;22) (q32;q12) resulting in the EWSR1/CREB1 gene, confirming a diagnosis of CCS. The translocation, histologic location, and long-standing clinical course exhibited in this case are exceptionally rare, and we hope to inform dermatologists of an uncommon presentation of CCS in an unexpected age group.

Primary Clear Cell Sarcoma of Bone: Report of a Case Arising from Distal Femur in a Pediatric Patient and Review of the Literature

Clear cell sarcoma is a rare mesenchymal tumor with melanocytic differentiation, firstly described by Enziger in 1965. It accounts for less than 1% of all soft tissue sarcomas and occurs predominantly in the extremities of adults. Primary clear cell sarcoma of bone is even rarer; current literature consists of only 13 cases with a mean age of presentation of 45-year-old, ranging from 18 to 81. Because of the overlapping expression of melanocytic markers, the differential diagnosis should be addressed with metastatic malignant melanoma and metastasis from clear cell sarcoma of soft parts. Essential for the diagnosis is the evidence of translocations t (12;22) or t (2;22) resulting respectively in EWSR1/ATF1 and EWSR1-CREB1 gene fusion. Clinical history and radiological assessment could help discriminate between bone or soft parts origin. We report an unusual case of clear cell sarcoma of distal femur involving a 13-year-old patient. Histological sections showed a malignant neoplasm composed of nests of uniform cells separated by fibrous septa, showing strong immunoreactivity for melanoma triple cocktail. Real Time-Polymerase Chain Reaction revealed the presence of the fusion product EWSR1-ATF1, confirming the diagnosis of clear cell sarcoma of bone. Our purpose was to revise the current literature in order to find common clinicalradiological features to this rare entity. To the best of our knowledge, our case is the first bone clear cell sarcoma arising from the distal femur in a pediatric patient described in the literature: it highlights the importance of considering this rare entity in the differential diagnosis of primary bone tumor, although extremely rare and of the use of molecular means to confirm the diagnosis.

Immunophenotype-Genotype Correlations in Clear Cell Sarcoma of Kidney-An Evaluation of Diagnostic Ancillary Studies.

The purpose of this study was to establish a reliable panel of antibodies for immunohistochemical corroboration of a diagnosis of clear cell sarcoma of kidney (CCSK), taking into consideration the various genotypic subsets of CCSK. We conducted full genotypic analysis for evidence of YWHAE-NUTM2, BCOR internal tandem duplication (ITD), and BCOR-CCNB3 in 68 archival cases of CCSK and then immunostained all cases for CCND1, TLE1, and BCOR along with 63 control samples representing tumor types that may enter into the differential diagnosis of CCSK, including 7 congenital mesoblastic nephromas, 2 desmoplastic small round cell tumors, 13 malignant rhabdoid tumors, 9 Ewing sarcomas/primitive neuroectodermal tumor, 5 synovial sarcomas, and 27 Wilms' tumors. Molecular assays showed that 54 CCSKs harbored a BCOR-ITD, 1 case expressed a YWHAE-NUTM2 fusion transcript while none expressed the BCOR-CCNB3 fusion. The remaining 13 CCSKs were designated "triple-negative" based on the molecular findings. CCND1 showed positive immunoreactivity across all subgroups. TLE1 was positive in 94% of cases, including 1 YWHAE-NUTM2 fusion-positive case. Three BCOR-ITD-positive tumors were TLE1-negative. BCOR immunostaining was most variable among subgroups, with triple-negative tumors showing the weakest staining. In all, 10/68 (15%) tumors did not stain for BCOR, of which 4 were triple-negative (4/13 = 31%) and 6 were BCOR-ITD-positive (6/54 = 11%). The single YWHAE-NUTM2-positive tumor showed strong staining for all 3 markers. No single case was negative for all 3 stains; however, 3 cases showed no reactivity for either BCOR or TLE1 of which 1 was triple-negative and 2 BCOR-ITD-positive. Having completed the first comprehensive evaluation of immunostaining of 68 fully genotyped CCSK tumors, we show herein that there is a rationale for the use of a small panel of antibodies to assist in the diagnosis of CCSK regardless of genotype, and we demonstrate that in combination CCND1, TLE1, and BCOR are compelling markers in aiding CCSK diagnosis.

Clear Cell Sarcoma of Lumbar Vertebra: A case report on how imaging improved diagnostics after initial suspicions.

Clear cell sarcoma is a rare malignant soft tissue neoplasm with a predilection for arising deep soft tissues adjacent to tendons and aponeuroses and fascial structures. This report presents a 32-year-old woman with low back pain and swelling, night sweat and lateral numbness in her right thigh for three months. MRI revealed a 4.0 x 5.8 cm vertebral lesion on the right lumbar region, without characteristics of a melanin rich tumor. Immunohistochemistry and fluorescence in situ hybridization confirmed diagnosis of clear cell sarcoma. The patient underwent a chemotherapy protocol. At four months post-surgery, CT revealed a soft tissue lesion in the right L3, suspected to be either a cancer relapse or harmless post-surgery lesion. Radiotherapy was performed in precaution of a relapse. At eleven months post-surgery, tumor relapse and multiple bone metastasis were observed. Combination of imaging methods improves diagnostics and subsequently differentiate clear cell sarcoma from other pathologies.

Review of the medical literature and assessment of current utilization patterns regarding the use of two common fluorescence in situ hybridization assays in the diagnosis of dermatofibrosarcoma protuberans and clear cell sarcoma.

Dermatofibrosarcoma protuberans (DFSP) is a tumor of intermediate malignancy, which in selected circumstances can pose difficulty in diagnosis. Clear cell sarcoma (CCS) is a very rare aggressive soft tissue sarcoma that can be difficult to distinguish histologically from melanoma. The current literature on t(17;22) COL1A1-PDGFB fluorescence in situ hybridization (FISH) assay in DFSP was reviewed. Also reviewed was the current literature on dual color break-apart EWSR1 FISH assay in CCS. Finally, the current utilization patterns of these tests was assessed in attendees of the American Society of Dermatopathology annual meeting (Chicago, 2016). The literature indicates that (17;22) COL1A1-PDGFB FISH assay has limited value for classic DFSP, where the diagnosis can be established by routine morphology and immunohistochemistry. Given the high specificity of the EWSR1 FISH assay and significant complexity in the diagnosis of CCS, this ancillary study is helpful in distinguishing CCS from melanoma. In attendees, t(17;22) COL1A1-PDGFB FISH testing for classic cases of DFSP is appropriately not being used by respondents. However, the literature sustains that it is useful in selected circumstances in which a definitive diagnosis is challenging. The majority of respondents are utilizing the EWSR1 FISH assay to distinguish CSS from melanoma as is supported by the literature.

Preoperative diagnosis of clear cell sarcoma of the kidney by detection of BCOR internal tandem duplication in circulating tumor DNA.

Clear cell sarcoma of the kidney (CCSK) is the second most common renal malignancy in children. The prognosis is poorer in CCSK than in Wilms' tumor, and multimodal treatment including surgery, intensive chemotherapy, and radiation is required to improve the outcome for children with CCSK. Histological evaluation is required for the diagnosis. However, biopsies of tumors to obtain diagnostic specimens are not routinely performed because of the risk of spreading tumor cells during the procedure. Recently, internal tandem duplication (ITD) of BCOR has been recognized as a genetic hallmark of CCSK. We herein established a novel BCOR-ITD-specific polymerase chain reaction method with well-designed primers, and then performed a liquid biopsy for cell-free DNA (cfDNA) obtained from plasma of three children with nonmetastatic renal tumors (stage II) and from one control. BCOR-ITD was positively detected in the cfDNA of two cases, both of which were later diagnosed as CCSK based on histological feature of the resected tumor specimen, while it was not detected for a normal control and a patient diagnosed with Wilms' tumor. Our study is the first one of preoperative circulating tumor DNA assay in pediatric renal tumors. The liquid biopsy method enables less invasive, preoperative diagnosis of CCSK with no risk of tumor spillage, which can avoid iatrogenic upstaging.

Difficulty in Cytological Diagnosis of Clear Cell Sarcoma - A Clinicopathological Correlation

Difficulty in Cytological Diagnosis of Clear Cell Sarcoma - A Clinicopathological Correlation

FNAC aided diagnosis of clear cell sarcoma of kidney: Report of two cases in infants

Clear cell sarcoma of kidney (CCSK) is a rare aggressive malignant renal neoplasm with a high metastatic potential. Its outcome has however, improved with the advent of doxorubicin based neoadjuvant chemotherapy. Here, we present two cases of CCSK in infants diagnosed on cytology followed by nephrectomy. The first case presented in the neonatal period and had the unusual histological finding of islands of cartilage. The second case presented at the age of eight months. The possibility of CCSK should, therefore, be considered in the differential diagnoses of renal masses in infants as well as neonates. Diagn. Cytopathol. 2017;45:761-765. © 2017 Wiley Periodicals, Inc.

Molecular genetics, diagnosis and management of clear cell sarcoma of hand

Synonyms: Clear cell sarcoma of soft tissue, Clear cell sarcoma of the tendons and aponeuroses, malignant melanoma of the soft parts. Background: Rodriguez-Martin, Ortiz-Cruz, Del Rio, Vivanco, & Lopaz-Amor in 2011 stated “Clear cell sarcoma is a high-grade soft tissue sarcoma seen in adolescents and young adults, with melanosytic differentiation typically involving tendons and aponeuroses”. Clear cell sarcoma of soft tissue (CCSST) was originally described by Dr. Franz M. Enzinger in 1965 as a distinct entity of tumors arising from tendons and aponeuroses in young adults. Clear cell sarcoma (CCS) of soft tissue is a rare sarcoma with morphologic similarities to malignant melanoma. They are characterized by a distinct genetic background including a chromosomal translocation t(12;22)(q13;q12), or a resultant EWSR1-ATF1 fusion gene. The lower limbs are involved more commonly. Clear cell sarcoma has been reported in other tissues such as bone, colon and gastrointestinal tract. The clear cell sarcoma that occurs in relation to the gastrointestinal tract has a variant fusion gene EWSR1-CREB1 and they are re-designated as gastrointestinal neuroectodermal tumor (GNET). Material and method: A 21 years old female with a chronic recurrent swelling of the left mid finger was diagnosed as epithelioid sarcoma on histopathological examination. Immunohistochemistry was done with basic tumor markers panel and a diagnosis of clear cell sarcoma was confirmed. Result: Immunohistochemistry staining is used for sub-typing of the tumor, predicts the prognosis of the tumor and also the response to the specific type of therapy.

Whole-exome sequencing identifies a somatic missense mutation of NBN in clear cell sarcoma of the salivary gland.

Clear cell sarcoma (CCS) is a rare, low-grade carcinoma commonly located in the distal extremities of young adults involving tendons and aponeuroses. CCS is characterized by its poor prognosis due to late diagnosis, multiple local recurrence, propensity to late metastases, and a high rate of tumor-related mortality. The genetic cause for CCS is thought to be EWSR1 gene translocation. However, CCS lacking a translocation may have other, as yet uncharacterized, genetic mutations that can cause the same pathological effect. A combination of whole‑exome sequencing and Sanger sequencing of cancer tissue and venous blood from a patient diagnosed with CCS of the salivary gland revealed a somatic missense mutation, c.1061C>T (p.P354L), in exon9 of the Nibrin gene (NBN). This somatic missense mutation led to the conversion of proline to leucine (p.P354L), resulting in deleterious effects for the NBN protein. Multiple-sequence alignments showed that codon354, where the mutation (c.1061C>T) occurs, is located within a phylogenetically conserved region. In conclusion, we here report a somatic missense mutation c.1061C>T (p.P354L) in the NBN gene in a patient with CCS lacking an EWSR1-ATF1 fusion. Our findings broaden the genotypic spectrum of CCS and provide new molecular insight that should prove useful in the future clinical genetic diagnosis of CCS.

Novel Karyotypes and Cyclin D1 Immunoreactivity in Clear Cell Sarcoma of the Kidney.

Pathological diagnosis of clear cell sarcoma of the kidney (CCSK) is challenging as it resembles blastemal Wilms tumor (WT) and other pediatric sarcomas, and does not have any distinctive immunophenotype. The YWHAE-FAM22 translocation t(10;17)(q22;p13) has been reported in a subset of CCSK. This translocation also occurs in high-grade endometrial sarcoma, in which it is associated with cyclin D1 overexpression. Hence we seek to determine YWHAE-FAM22 translocation status and cyclin D1 immunoreactivity in a series of local CCSK cases. Of 8 CCSK cases from 7 patients identified, no CCSK had the YWHAE-FAM22 fusion transcript by reverse transcriptase-polymerase chain reaction. Novel karyotypes were identified for 2 cases: 1 had t(2;13)(q13;q22) and the other t(3:17)(q29;p11.2). Excluding a case with poor tissue section antigenicity, 7 of 7 CCSKs (100%) showed diffuse and strong nuclear cyclin D1 staining. Cyclin D1 immunohistochemistry was also performed on tissue microarrays of other pediatric renal tumors: blastemal areas of 18 WT cases were negative; 6 rhabdoid tumors and 1 metanephric adenoma showed patchy and weak staining; 3 mesoblastic nephromas and 18 of 29 neuroblastomas had positive staining. Cyclin D1 immunohistochemistry helps distinguish CCSK from blastemal WT and metanephric adenoma and rhabdoid tumors, but not from neuroblastomas and mesoblastic nephromas. Cyclin D1 overexpression in CCSK is not contingent on YWHAE-FAM22 translocation, and cyclin D1 inhibition may potentially be explored as a targeted therapeutic strategy in CCSK.

Clear Cell Sarcoma of Kidney in a Neonate

A rare case of clear cell sarcoma of kidney (CCSK) especially in a neonate presented as abdominal mass in left flank. He was hospitalized, investigated and operated upon. Histopathology confirmed the diagnosis of clear cell sarcoma of the kidney. Post-operatively, chemotherapy was given according to the NWTS-5 protocol. During follow-u, the patient has shown good recovery after 7 months of surgery.

Clear cell sarcoma originating in the anterior mediastinum

A 34-year-old man with intermittent chest pain had a 60-mm mass in the anterior mediastinum. A CT-guided needle biopsy revealed that the tumor was composed of atypical small cells and was positive for HMB-45 without cytoplasmic melanin pigmentation. These results suggested a diagnosis of malignant melanoma (MM) or clear cell sarcoma (CCS). EWS gene rearrangement was detected by fluorescence in situ hybridization, resulting in the definite diagnosis of CCS. Sarcomas originating in the mediastinum account for only 1 % of all sarcoma cases. CCS is a rare soft tissue sarcoma, which usually occurs in the tendons and aponeuroses and is often misdiagnosed as MM because of similar immunophenotypes. There is only one reported case of a primary CCS of the mediastinum. There is no standard treatment for CCS, but for metastatic MM, dacarbazine, ipilimumab, and BRAF-inhibitors can be treatments of choice. Thus, differential diagnoses are important to determine treatment strategies. Meticulous observation of skin lesions and pathological and molecular diagnoses, including EWS gene rearrangement, is recommended in cases with mediastinal tumors suspected of MM or CCS.

A rare case of primary clear cell sarcoma of the pubic bone resembling small round cell tumor: an unusual morphological variant

BackgroundClear cell sarcoma (CCS) and malignant melanoma share overlapping immunohistochemistry with regard to the melanocytic markers HMB45, S100, and Melan-A. However, the translocation t(12; 22)(q13; q12) is specific to CCS. Therefore, although these neoplasms are closely related, they are now considered to be distinct entities. However, the translocation is apparently detectable only in 50%–70% of CCS cases. Therefore, the absence of a detectable EWS/AFT1 rearrangement may occasionally lead to erroneous exclusion of a translocation-negative CCS. Therefore, histological assessment is essential for the correct diagnosis of CCS. Primary CCS of the bone is exceedingly rare. Only a few cases of primary CCS arising in the ulna, metatarsals, ribs, radius, sacrum, and humerus have been reported, and primary CCS arising in the pubic bone has not been reported till date.Case presentationWe present the case of an 81-year-old man with primary CCS of the pubic bone. Histological examination of the pubic bone revealed monomorphic small-sized cells arranged predominantly as a diffuse sheet with round, hyperchromatic nuclei and inconspicuous nucleoli. The cells had scant cytoplasm, and the biopsy findings indicated small round cell tumor (SRCT). Immunohistochemical staining revealed the tumor cells to be positive for HMB45, S100, and Melan-A but negative for cytokeratin (AE1/AE3) and epithelial membrane antigen. To the best of our knowledge, this is the first case report of primary CCS of the pubic bone resembling SRCT. This ambiguous appearance underscores the difficulties encountered during the histological diagnosis of this rare variant of CCS.ConclusionAwareness of primary CCS of the bone is clinically important for accurate diagnosis and management when the tumor is located in unusual locations such as the pubic bone and when the translocation t(12; 22)(q13; q12) is absent.