Immunohistochemical expression of p16 in lipoblastomas

The Conundrum of Dedifferentiation in a Liposarcoma at a Peculiar Location: A Case Report and Literature Review

Dedifferentiated liposarcoma of the deep soft tissue of the lower extremities is an infrequent finding. Myxoid liposarcoma is considered the most common soft tissue neoplasia arising in this anatomic region. Divergent differentiation usually occurs within well-differentiated liposarcoma and is exceedingly rare in a myxoid liposarcoma. We report a 32-year-old man who developed a dedifferentiated liposarcoma of the thigh on the background of a pre-existing myxoid liposarcoma. The gross examination of the surgical specimen showed a 11/7/2 cm tumour mass with solid tan-grey areas and focal myxoid degeneration. The microscopic examination revealed a malignant lipogenic proliferation, containing round cells with hyperchromatic nuclei and atypical lipoblasts, confined to the basophilic stroma with a myxoid aspect. Abrupt transition towards a hypercellular, non-lipogenic area consisting of highly pleomorphic spindle cells with atypical mitotic figures was also noted. Immunohistochemical staining was performed. Tumour cells in the lipogenic area were intensely positive for S100 and p16, and CD34 staining highlighted an arborizing capillary network. The dedifferentiated tumour areas showed positive MDM2 and CDK4 staining within neoplastic cells, with the Ki 67 proliferation marker expressed in approximately 10% of the cells. Wild-type TP53 protein expression pattern was documented. Thus, the diagnosis of a dedifferentiated liposarcoma was established. This paper aims to provide further knowledge about liposarcomas with divergent differentiation at peculiar locations, emphasizing the importance of histopathologic examination and immunohistochemical analysis for establishing the diagnosis and assessing the therapeutic response and prognosis of this condition.

Immunohistochemical Expression of p16 and CDK4 in Soft Tissue Tumors

BACKGROUND AND OBJECTIVES

 The aim of this study was to determine the immunohistochemical expression of p16 (p16^INK4a) and cyclin-dependent kinase 4 (CDK4) and CDK4 markers in various lineages of soft tissue tumors and to evaluate their role in differentiating atypical lipomatous tumors/well-differentiated liposarcomas from benign lipomas.

MATERIAL AND METHODS

A total of 70 cases of both excisional and incisional biopsies of soft tissue tumors were included in this study. Histopathological examination was done by using formalin-fixed, paraffin-embedded tissue samples. After that, we performed IHC expressions of p16 and CDK4 markers on the unstained slides of these soft tissue tumors.  Results: Immunohistochemical study showed that positive expressions of p16, CDK4, and combined (p16+CDK4) markers were 51.4%, 10.0%, and 12.9%, respectively in soft tissue tumors. Positive p16 expression was observed among a higher proportion of malignant cases (66.7%) as compared to benign (20.0%) and intermediate (50.0%) cases. This difference was found to be statistically significant (p=0.009). Negative expression of only CDK4 and combined (p16 and CDK4) were observed among a higher proportion of benign as compared to malignant and intermediate cases (90.0% vs. 78.6% & 75.0%, p=0.393 and 65.0% vs. 26.2% & 37.5%, p=0.028, respectively). This difference was not found to be statistically significant. For adipocytic tumors, the majority of malignant and intermediate tumors had positive p16 (7/7; 100%) and CDK4 (6/7; 85.7%) immunohistochemical expression. These differences were found to be statistically significant.

CONCLUSION

Immunohistochemical marker p16 can be used to differentiate between malignant and benign soft tissue tumors. Amongst adipocytic tumors, combination of p16 and CDK4 immunohistochemical expression can be used to differentiate liposarcomas from benign ones.

Lipoblastoma in one adult and 35 pediatric patients: Retrospective analysis of 36 cases

Lipoblastoma is a rare benign mesenchymal neoplasm that typically occurs at various sites in infants and children but may also occur in adults. Thus, differential diagnoses are often performed. To understand this tumor type, the present study described clinicopathological features, diagnosis and differential diagnosis of different morphological lipoblastomas. A single-institution retrospective review of 36 lipoblastoma cases diagnosed between 2015 and 2021 was performed. Formalin-fixed paraffin-embedded tissue was used for S-100, CD34, P16 and desmin immunohistochemistry analysis, along with rapid fluorescence in situ hybridization (FISH) detection with pleiomorphic adenoma gene 1 (PLAG1). The 36 cases included 14 females and 22 males [age range, 7 days to 33 years (median, 16.5 years); 28 patients were aged ≤3 years] and the tumors were located in the trunk (n=16), limbs (n=12), head and neck (n=6), and perineum (n=2). Histologically, lipoblastomas were divided into classic (n=15), lipoma-like (n=13) and myxoid (n=8) subtypes. They comprised lobules of mature adipose tissue of varying size and a fine capillary network surrounded by mucinous stroma. Single- or multivesicular lipoblasts positive for S-100 (29/36, 81%) were observed, with occasional mature adipocytes. Peripheral vessels and cytoplasm of primitive mesenchymal cells were diffusely positive for CD34 (36/36, 100%), whereas primitive mesenchymal cells and striated muscle tissue were positive for desmin (26/36, 72%). Most tumor cells were negative while only few were positive for P16 (8/36, 22%). FISH revealed PLAG1 breakage and rearrangement in 24/32 (75%) patients. In total, 28 patients were followed up post-operatively (range, 2-84 months; median, 41 months; 3 patients relapsed and 8 were lost to follow-up). In conclusion, diagnosis of a typical lipoblastoma is not difficult and PLAG1 breakage detection is key for the diagnosis.

Update of Pediatric Lipomatous Lesions: A Clinicopathological, Immunohistochemical and Molecular Overview

Lipomatous neoplasms are a rare entity in the pediatric population, comprising less than 10% of soft tissue tumors in the first two decades of life. Some characteristics of pediatric adipocytic tumors are analogous to their adult counterparts, some pediatric lipomatous lesions however harbor unique features. In recent years, there have been significant advances in the understanding of the pathogenesis and hence in the classification and treatment of pediatric adipocytic tumors. This literature-based article will provide a review of the presently known clinicopathological, immunohistochemical and molecular features of pediatric lipomatous lesions.

Lipoblastoma: Diagnosis and surgical considerations

Lipoblastoma (LB) and lipoblastomatosis (LBS) are uncommon benign mesenchymal tumors of embryonal fat, occurring almost exclusively in infancy and early childhood. These fast-growing tumors have an excellent prognosis if properly treated. Eight consecutive children having pathologically demonstrated LB treated by the same surgical team were retrospectively reviewed. There were 5 boys and 3 girls between 7 to 36 months (median age 22 months). The localization of the tumors was on the thigh (1 case), abdomen (2 cases), axillary and pectoral region (1 case) paragluteal region (1 case), lumbar area (1 case), inguinal-scrotal (1 case), and in one case, presacral, gluteal and perirectal region (1 case). Five were focal and in 3 cases an infiltrative growth pattern was observed. One case exhibited a gross appearance resembling sacrococcygeal teratoma, with associated Dravet syndrome. No recurrence was noted in our series, after a mean follow-up of 28 months post operatory. Despite its rareness, LB must be kept in mind when diagnosing a rapidly growing fatty mass in children. Even when dealing with very large abdominal LB, complete surgical excision is possible, with an excellent prognosis. Due to the relatively high recurrence rate noted in the literature, particularly in LBS, follow-up is extremely important.

Rapidly Growing Facial Tumor in a 5-Year-Old Girl

The aim of this study is to describe the clinical, radiological and histological characteristics that define lipoblastomas with special emphasis on differential diagnosis. The patient is a 5-year-old girl who consulted for a rapidly growing lower cheek tumor. This study analyzes, evaluates, and discusses the issues that need to be addressed throughout the process that affect treatment planning and provides an updated review of these rare head-and-neck tumors.

Follow-up outcomes of pediatric patients who underwent surgical resection for lipoblastomas or lipoblastomatosis: a single-institution experience with a systematic review and meta-analysis

PURPOSE

The objective of this study was to examine the long-term outcomes of pediatric patients who underwent surgical resection for lipoblastoma and lipoblastomatosis (LB/LBM).

METHODS

A single-center retrospective study of pediatric patients with LB/LBMs seen between 1991 and 2015 was conducted. A systematic review, including studies published prior to late August 2018, was performed. Using a random effect meta-analysis, pooled weighted proportions and unadjusted odds ratios (OR) with 95% confidence intervals (CI) were calculated.

RESULTS

The retrospective study included 16 patients, while the systematic review included 19 published studies consisting of 381 patients. Among 329 (82%) patients with follow-up information, the pooled recurrence rate was 16.8% (95% CI 10.9-23.5%; I² = 59%). The reported time to recurrence ranged from < 1 to 8 years. Recurrence risk was greater for incomplete (n = 34) than complete resection (n = 150): OR 11.4 (95% CI 3.0-43.6; I² = 43%). LBMs (n = 35) had a greater recurrence risk than LBs (n = 116): OR 5.5 (95% CI 1.9-15.9; I² = 0%). Recurrences were higher for studies with approximately ≥ 3 years of follow-up versus studies with < 3 years of follow-up.

CONCLUSION

Recurrences are more likely to occur with LBMs and/or incomplete resection. Follow-up beyond 3-5 years should be considered given that the recurrence risk appears to be greater in the long-term.

Cytoplasmic p16 Is Expressed in Normal Brown Fat and Hibernomas

White adipose tissue browning has emerged as a putative therapy of obesity, and studies in mice have shown that Cdkn2a is implicated in white-to-brown transition. However, the role of Cdkn2a product p16 has been never studied in human brown fat tissue. The aim of the study is to investigate the expression of p16 in normal brown fat and in hibernoma, a lipoma containing brown fat-like adipocytes. Ten normal brown fat tissues and 5 hibernomas were immunohistochemically studied for p16 expression. Nearby white adipose tissue was used for comparison. All brown fat and hibernomas specimens express p16 in a cytoplasmic manner. Neighboring white adipose tissue is negative for p16 expression. Thus, cytoplasmic p16 may be associated with fat tissue browning.

Diagnostic importance of clinicopathologic features and p16, CD34, MDM2 expression in differential diagnosis of adipocytic tumors

OBJECTIVE

The aim of this study was to investigate the immunohistochemical stain profiling of adipocytic tumors.

METHODS

From our archive files between the years of 2012-2018, excised, formalin-fixed and paraffin-embedded adipocytic tumors were retrospectively screened and 61 subjects were selected. The gender, age, tumor location and tumor diameter were evaluated. The cases were investigated in terms of p16, CD34, MDM2 expression and clinicopathological information.

RESULTS

Of the 61 patients included in the study, we found that 2 had hibernoma, 4 had lipoblastoma, 14 had spindle cell lipoma (SCL), 10 had lipoma, 20 had atypical lipomatous tumor/well differentiated liposarcoma (ALT/WDL), and 11 had dedifferentiated liposarcoma (DDL). In terms of diameter, ALT/WDL and DDL were significantly different from the others (p=0.001, p=0.001, respectively). There was a significant difference between the groups according to the location (p=0.001). 35% (7/20) of ALT/WDLs were in the lower extremities (thighs) and 35% (7/20) were located in the retroperitoneal region. 70% of DDLs (7/11) were located in the retroperitoneum. When CD34 expression was evaluated among the groups, a significant difference was observed (p=0.001). CD34 was positive in 92.9% of SCL cases. p16 immunoreactivity was significantly different between the groups (p=0.001). p16 expression was observed in 50.5% of ALT / WDL cases and 79% of DDL cases.

CONCLUSION

p16 and CD34 expression are valuable in the differential diagnosis of lipomatous tumors when radiological and clinical considerations do not help to differential diagnosis of adipocytic tumors.

LEVEL OF EVIDENCE

Level IV, Therapeutic Study.

Intrascrotal lipoblastoma in adulthood

This case report describes the case of a 37-year-old man that noticed an intrascrotal right mass with 1 month of evolution. During physical exam presented with a large mass at the inferior portion of the right testicle, clearly separated from the testicle, with a tender consistency and mobile. An ultrasound was performed that showed a solid and subcutaneous nodular lesion, extra testicular, heterogeneous, measuring 7.2 cm. Pelvic magnetic resonance imageMRI showed a lesion compatible with a lipoma. The patient was subjected to surgical excision of the lesion by scrotal access, having histology revealed a lipoblastoma (LB) of the scrotum. Histological diagnosis was obtained by microscopic characteristics (well-circumscribed fatty neoplasm) and immunohistochemistry (stains for CD34, S100 protein and PLAG1 were positive; stains for MDM2 and CDK4 were negative). LB is extremely rare after adolescence in any location, being this first described case of intrascrotal LB described in adulthood.

Symptomatic and lethal congenital primary cardiac rhabdomyoma

Background

Congenital tumors, including mesenchymal rhabdomyoma, are highly infrequent. The combination of a congenital tumor and rhabdomyoma is rarer yet, even more so when primary origin is in the heart.

Case presentation

We present a case of fetal hydrops fetalis, wherein the post-mortem exam revealed a cardiac tumor more than twice the size of the heart itself; histological study confirmed primary rhabdomyoma involving the left ventricle.

Conclusion

It is essential to keep in mind that fetal tumors should always be differentiated from malformations; in fetuses tissue immaturity must be taken into account for categorization; despite benign labeling, they can be lethal.

Myxoid Lipoblastoma and Mimickers on Fine-Needle Biopsy in a Child

Image-guided percutaneous core needle biopsy is a standard and safe procedure for the diagnosis of both solid and hematological malignancies in children. Despite recent improvements, nondiagnosis biopsies persist. Lipoblastoma is a benign adipocytic tumor composed of embryonal fat admixed with mature adipocytes and occurring before the age of 1 year in one-third of cases. Lipoblastoma is usually easily diagnosed, but in some cases, diagnosis may be difficult on percutaneous biopsies, when the lipoblastic component is not well represented or when the tumor contains a prominent myxoid component mimicking other myxoid tumors. We report here a case of lipoblastoma with a predominant myxoid component and discuss differential diagnosis of myxoid lesions of infancy. In such cases, pathologic examination enhanced by adjunct techniques, such as immunohistochemistry and cytogenetic or molecular genetic studies, is needed to achieve accurate diagnosis, particularly on fine-needle biopsies.

Human papillomavirus infection is not involved in esophageal verrucous carcinoma

Verrucous carcinoma of the esophagus (VCE) is a rare variant of squamous cell cancer, with a puzzling clinical, etiological, and molecular profile. The etiological involvement of human papillomavirus (HPV) in the cancer's natural history is controversial. This study considers 9 cases of VCE, focusing on patients' clinical history before surgery, histologic phenotype, immunophenotype (epidermal growth factor receptor [EGFR], E-cadherin, cyclin D1, p16, and p53 expression), HPV infection, and TP53 gene mutational status (exons 5-8). Using 3 different molecular test methods, not one of these cases of VCE featured HPV infection. The only case with synchronous nodal metastasis was characterized by a TP53 missense point mutation in association with high EGFR and low E-cadherin expression levels. In conclusion, HPV infection is probably not involved with VCE, while TP53 gene mutation, EGFR overexpression, and E-cadherin loss might fuel the tumor's proliferation and lend it a metastatic potential.

Expression of MDM2 and p16 in angiomyolipoma

Angiomyolipoma (AML) arises primarily from the kidney but may grow into the retroperitoneal space mimicking a primary retroperitoneal tumor. Fine needle aspiration (FNA) and core needle biopsy of AML, particularly the fat-predominant variant, may be difficult to distinguish from retroperitoneal well-differentiated liposarcoma (WDLS) or lipoma. Commonly used immunomarkers, MDM2 and p16, have proven useful in diagnosing WDLS and dedifferentiated liposarcoma (DDLS), while HMB45 and Melan-A are melanocyte-related markers characteristically expressed in AML. In this study, we investigated the utility of MDM2 and p16 along with HMB45 and Melan-A immunohistochemical analysis in distinguishing AML from WDL/DDLS or lipoma. Immunohistochemically, AMLs demonstrated focal MDM2 expression (40% of cases) and focal/diffuse expression of p16 (60%). AMLs marked focally or diffusely with HMB45 (76% of cases) and Melan-A (96%). These latter two immunomarkers were not expressed in any of the WDLS/DDLSs or lipomas tested. WDLS/DDLSs showed focal/diffuse expression of MDM2 (91% of cases) and p16 (97%). While focal expression of MDM2 and p16 was observed in 14% and 67% of lipomas, respectively, no lipoma exhibited diffuse MDM2 positivity. In our hands, MDM2 expression by itself cannot exclude the diagnosis of AML or lipoma, and p16 alone is not helpful in separating AML and conventional lipoma from WDLS/DDLS. However, along with morphology, an immunohistochemical battery including HMB45, Melan-A, MDM2 and p16 are useful in distinguishing AML from WDLS/DDLS or lipoma. For equivocal cases, fluorescence in situ hybridization for MDM2 should be performed.

Lipoblastoma: a clinicopathologic review of 23 cases from a major tertiary care center plus detailed review of literature

Objective

Lipoblastoma is a rare neoplasm that occurs mostly in infants and children. Although benign, it has a tendency for local recurrence.

Results

Clinical and pathological features of 23 cases of lipoblastoma described. Patients’ age ranged from 8 months to 18 years with mean and median age 4.1 and 2.5 years, respectively. Male:female ratio was 2.8:1. Most common sites were lower extremities (9 cases), followed by abdominal cavity and retroperitoneum (4 cases), and scrotum/groin (3 cases). Grossly, 22 tumors were well circumscribed and multi nodular. All cases showed lobules composed of adipocytes and lipoblasts with intervening fibrous septa and fine vascular network. Myxoid change, capsule formation and septation were seen in all cases. Zonation was seen in 2 cases. Follow-up was available in 14 out of 23 patients. Of these, 13 were alive and free of disease with no evidence of any recurrent lesion. One patient with a mediastinal infiltrating lipoblastoma experienced 4 recurrences. Lipoblastoma is a benign adipocytic neoplasm of infants and young children. Correlation of clinical and histological features helps in reaching a correct diagnosis. Owing to a high recurrence rate following incomplete resection, a complete resection is essential. Prognosis is excellent after complete resection.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3153-8) contains supplementary material, which is available to authorized users.