Perilipin and adipophilin expression in sebaceous carcinoma and mimics

Extra-Ocular Sebaceous Carcinoma in Situ of the Arm of an Elder Male: An Unusual Presentation in an Atypical Location

Background. Sebaceous carcinoma in situ outside the ocular region is an exceedingly uncommon. It is an intraepidermal neoplasm originating from sebaceous glands limited to the epidermis with no invasion into the underlying dermis or beyond. Although sebaceous carcinoma in situ is predominantly observed in ocular regions, particularly the eyelids, instances of its occurrence in extraocular locations are infrequent, with only a limited number of examples reported in the literature. Case Presentation. A 63-year-old man presented with a left posterior arm lesion. Microscopic examination revealed a proliferation of poorly differentiated atypical neoplastic sebocytes confined to the epidermis with pleomorphic nuclei, prominent nucleoli, and clear cell changes. The neoplastic cells demonstrated positive staining for adipophilin, androgen receptor, epithelial membrane antigen, P63, BerEP4, and keratin 7. Microsatellite instability markers showed preserved nuclear staining for MLH1, PMS2, MSH2, and MSH6. A definitive diagnosis of sebaceous carcinoma in situ was rendered. Discussion. The distinctive histopathologic characteristics typically involve the presence of atypical sebaceous cells confined within the epidermis. Atypical cells often exhibit enlarged nuclei, increased mitotic activity, and prominent nucleoli. A panel of epithelial membrane antigen, adipophilin, and androgen receptors is essential for ensuring an accurate diagnosis. Conclusion. This report underscores the importance of considering sebaceous carcinoma in situ in diagnosis in atypical locations, emphasizing the need for a comprehensive histopathologic examination and immunohistochemical staining panel. This article aims to demonstrate the rarity of sebaceous carcinoma in situ in extraocular sites to broaden our understanding of its diverse clinical presentations.

Clinicopathologic Features of Eyelid Sebaceous Gland Carcinoma Requiring Immunohistochemical Diagnosis

Introduction

The aim of the study was to evaluate the clinicopathological features of eyelid sebaceous gland carcinoma (SGC), which requires immunohistochemical examination for a definitive diagnosis.

Methods

Twenty-seven patients with a final diagnosis of eyelid SGC at Toyama University Hospital between April 2016 and April 2022 were retrospectively studied. In cases with a strong clinical suspicion of SGC, if the initial pathological diagnosis by hematoxylin-eosin staining was non-SGC, additional detailed pathology was performed, including immunostaining for adipophilin (ADP) and androgen receptor (AR).

Results

Five patients (18.5%) had a diagnosis other than SGC, including three with squamous cell carcinoma (SCC), one with basal cell carcinoma, and one with Bowen disease. In these 5 cases, detailed pathology, including immunostaining for ADP and AR, was performed again, which ultimately led to the diagnosis of SGC. ADP was positive in all 5 cases, and AR was positive in 4 cases. The 3 patients diagnosed with SCC were characterized by a high Ki-67 index, active mitosis, and relatively low differentiation.

Conclusion

SGC can be pathologically diagnosed in other cancers, such as SCC and BCC. When SCC was diagnosed, it was often hypo-differentiated and required more attention. Immunostaining for ADP and AR is invaluable for confirming SGC diagnosis.

Hidradenocarcinoma: A Case Series From the Scripps Clinic With a Systematic Review of the Literature

BACKGROUND

Hidradenocarcinoma (HAC) is a rare adnexal carcinoma. To the best of the authors' knowledge, there are no published systematic reviews on HAC.

OBJECTIVE

To incorporate a case series from the authors' institution and systematically integrate reported information to provide a reference tool for optimization of diagnosis and management.

METHODS

A comprehensive MEDLINE search was conducted from database inception to 2021 using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. This yielded 225 studies with 165 cases of HAC. References of included articles were also searched. In addition, 9 patients with HAC were identified from the authors' institution over the past 10 years.

RESULTS

The mean age of HAC presentation is 60 years with a slight male predilection (60%). The head and neck is the most commonly affected region. Over 36% of cases either presented with metastatic disease or went on to metastasize. The most common treatment type was wide local excision, followed by Mohs micrographic surgery.

CONCLUSION

Early detection with accurate histologic interpretation is prudent in all cases of HAC. Wide local excision is the current first-line treatment. However, Mohs micrographic surgery offers complete marginal analysis with evidence of reduced risk of metastasis and better outcomes compared with wide local excision. Currently, there are no National Comprehensive Cancer Network guidelines for the treatment of HAC, and consensus guidelines are limited to tumor and nodal metastasis staging provided by the American Joint Committee on Cancer, eighth edition. Thus, this case series and systematic review integrates important aspects of diagnosis, workup, and management of HAC.

Lipid droplets provide metabolic flexibility for cancer progression

A hallmark of cancer cells is their remarkable ability to efficiently adapt to favorable and hostile environments. Due to a unique metabolic flexibility, tumor cells can grow even in the absence of extracellular nutrients or in stressful scenarios. To achieve this, cancer cells need large amounts of lipids to build membranes, synthesize lipid-derived molecules, and generate metabolic energy in the absence of other nutrients. Tumor cells potentiate strategies to obtain lipids from other cells, metabolic pathways to synthesize new lipids, and mechanisms for efficient storage, mobilization, and utilization of these lipids. Lipid droplets (LDs) are the organelles that collect and supply lipids in eukaryotes and it is increasingly recognized that the accumulation of LDs is a new hallmark of cancer cells. Furthermore, an active role of LD proteins in processes underlying tumorigenesis has been proposed. Here, by focusing on three major classes of LD-resident proteins (perilipins, lipases, and acyl-CoA synthetases), we provide an overview of the contribution of LDs to cancer progression and discuss the role of LD proteins during the proliferation, invasion, metastasis, apoptosis, and stemness of cancer cells.

Upregulated MYC expression and p53 mutations may contribute to the oncogenesis of canine Meibomian gland carcinomas

Sebaceous carcinomas of the human ocular adnexa commonly exhibit pagetoid spread, mutations in tumor-suppressor genes, and protooncogene copy number gain. Sebaceous carcinomas are rarely reported in other species, and while the Meibomian gland (MG) represents the most common ocular adnexal structure of the canine eyelid to develop neoplasia, most are clinically and histologically benign. The objective of this study was to compare molecular features of canine MG carcinomas and adenomas. Two retrospectively identified MG carcinomas were subject to immunohistochemistry and qPCR. When compared with normal glands, MYC was upregulated in benign and malignant MG neoplasms. Aberrant p53 expression was restricted to the nuclei of intraepithelial neoplastic cells in MG carcinomas. Adipophilin expression was diminished in MG neoplasms compared with the normal MG. Our findings, if confirmed in a larger cohort of cases, could suggest that MG oncogenesis in a dog may exhibit similar molecular features as their human counterparts.

Integrated Whole-Exome and Transcriptome Sequencing Indicated Dysregulation of Cholesterol Metabolism in Eyelid Sebaceous Gland Carcinoma

Purpose

To identify the molecular background of eyelid sebaceous gland carcinomas (SCs), we conducted the integrated whole-exome sequencing and transcriptome sequencing for eyelid SCs in this study.

Methods

The genetic alterations were studied by whole-exome sequencing, and the messenger RNA expression was studied using Oxford Nanopore Technologies (ONT) in five paired fresh eyelid SC tissues and adjacent normal tissues. Integrated analysis of exome and transcriptomic information was conducted for filtering candidate driver genes. Protein-protein interaction (PPI) network of filtered candidate genes was analyzed by STRING. The protein expression was verified by immunohistochemistry in 29 eyelid SCs and 17 compared normal sebaceous gland tissues.

Results

The average numbers of pathogenic somatic single-nucleotide variants (SNVs) and indels in eyelid SCs were 75 and 28, respectively. Tumor protein p53 (TP53), zinc finger protein 750 (ZNF750), filaggrin 2 (FLG2), valosin-containing protein (VCP), and zinc finger protein 717 (ZNF717) were recurrent mutated genes. A mean of 844 differentially expressed genes (DEGs) were upregulated, and 1401 DEGs were downregulated in SC samples. The intersection of DEG-based pathways and mutation-based pathways was mainly involved in microbial infection and inflammation, immunodeficiency, cancer, lipid metabolism, and the other pathways. The intersection of DEGs and mutated genes consisted of 55 genes, of which 15 genes formed a PPI network with 4 clusters. The PPI cluster composed of scavenger receptor class B member 1 (SCARB1), peroxisome proliferator-activated receptor γ (PPARG), peroxisome proliferator-activated receptor γ coactivator 1α (PPARGC1A) was involved in cholesterol metabolism. The expression of SCARB1 protein was found to be increased, whereas that of PPARG protein was decreased in eyelid SCs compared to that in the normal sebaceous glands.

Conclusions

Increased SCARB1 and decreased PPARG indicated that dysregulation of cholesterol metabolism might be involved in carcinogenesis of eyelid SCs.

Translational Relevance

The malfunction in cholesterol metabolism might advance our knowledge of the carcinogenesis of eyelid SCs.

Adipophilin: roles in physiology and pathology

Adipophilin (ADRP/ADPH/PLIN2), an adipocyte differentiation-related protein, is highly expressed at a very early time during the differentiation of adipocytes. It assists in the formation and maintenance of intracellular lipid droplets and plays a role in regulating the physiological functions of the body. More and more studies indicate that it is involved in the occurrence and development of a variety of glycolipid metabolic diseases and tumours. In this review, we comprehensively stated the expression and functions of adipophilin and introduced its roles in physiology and pathology.

Perilipin 1 and adipophilin immunoexpression suggests the presence of lipid droplets in tooth germ, ameloblastoma, and ameloblastic carcinoma

BACKGROUND

Increased lipogenesis and lipid droplet accumulation are observed in diverse tumors, and these processes are associated with poor prognosis in several tumors, representing potential therapeutic targets. The presence of lipid droplets in odontogenic tissues and/or tumors is unknown.

METHODS

Immunohistochemistry for perilipin 1 and adipophilin was performed in 12 human tooth germs (TG), 27 conventional ameloblastoma (AM), and 8 ameloblastic carcinoma (AC) samples. Cytoplasmic staining was analyzed using an immunoreactive score (IRS), and the results were compared for the TG, AM, and AC samples by Kruskal-Wallis test followed by Dunn's post-test and confirmed by Mann-Whitney U test.

RESULTS

Perilipin 1 was negative in 91.7% of the TG samples, positive in 48.2% of the AM samples, and positive in 87.5% of the AC samples. Adipophilin was positive in 100% of the TG samples, 92.6% of the AM samples, and 100% of the AC samples. The perilipin 1 and adipophilin IRS revealed statistically significant differences between the TG, AM, and AC samples (p = .007 and p = .018, respectively). The perilipin 1 levels among the TG and AC samples were statically significant (**p = .0085), as well as the adipophilin levels when TG and AM samples were compared (**p < .0029).

CONCLUSIONS

Adipophilin exhibits significant activity in human tooth development. The immunoexpression of perilipin 1 and adipophilin in the AM and AC samples suggests the presence of lipid droplets, providing further evidence of metabolic alterations in these tumors. Additional studies with larger samples and alternative techniques are necessary to confirm these findings.

Comparison of adipophilin and recently introduced PReferentially expressed Antigen in MElanoma immunohistochemistry in the assessment of sebaceous neoplasms: A pilot study

BACKGROUND

We and others have noticed consistent staining of sebaceous glands with PReferentially expressed Antigen in MElanoma (PRAME). We aimed to determine whether PRAME was as sensitive, specific, and interpretable as adipophilin for distinguishing sebaceous neoplasms (SNs) from other neoplasms.

METHODS

Twenty SNs and 32 control cases were stained for PRAME and adipophilin. Extent of staining was scored as follows: 0, no staining; 1, <5% positivity; 2, 5% to 50% positivity; and 3, >50% positivity. Intensity was scored as negative, weak, moderate, or strong. A composite score was determined by adding the scores for extent and intensity.

RESULTS

PRAME had positive composite scores in all 20 SNs in the more differentiated areas, whereas adipophilin had positive composite scores in 19/20 cases. PRAME showed positivity in the basaloid cells in 15/16 cases, whereas adipophilin was positive in 14. Among controls, PRAME and adipophilin had positive composite scores in 3/32 cases and 6/32 cases, respectively.

CONCLUSIONS

PRAME and adipophilin are comparable in terms of distribution and intensity for staining sebocytes. In the basaloid cells, PRAME expression is often more diffuse and easier to detect than adipophilin. In comparing the SNs to the controls, PRAME was more sensitive and more specific than adipophilin. PRAME could be used as an additional marker of sebaceous differentiation in everyday practice.

Twenty-Eight Cases of Extraocular Sebaceous Carcinoma: A Correlative Clinicopathological and Immunohistochemical Analysis of Extraocular Sebaceous Carcinomas and Benign Sebaceous Gland Tumors

ABSTRACT

Extraocular sebaceous carcinoma (ESC) is a rare appendiceal skin tumor. In contrast to ocular sebaceous carcinoma, information about the exact cellular architecture of these lesions is scarce and the histogenesis of ESC is unknown. Here, we extend our previous study and investigate 28 extraocular carcinomas in comparison to 54 benign sebaceous tumors and 8 cases of normal sebaceous glands using a broad spectrum of antibodies against p63, several keratins, adipophilin, EMA, Ki67, androgen receptor, and mismatch repair proteins. This observational study demonstrates that p63- and K5/14-positive basaloid cells are key cells in normal sebaceous gland and in all sebaceous tumors and that these basaloid cells give rise to EMA+, adipophilin+ sebocytes, and K5/14+, K7±, K10± ductal structures. Finally, about half of ESC is associated with superficial in situ neoplasia, which provides evidence that at least part of these carcinomas arises from flat superficial in situ carcinoma. In contrast to the normal sebaceous gland, about half of all sebaceous tumors lack keratin K7. MMR protein IHC-profiles role will be discussed.

Molecular profiling of a primary cutaneous signet-ring cell/histiocytoid carcinoma of the eyelid

Primary cutaneous signet-ring cell/histiocytoid carcinoma of the eyelid is a rare and aggressive neoplasm. Fewer than 50 cases have been reported in the literature, and the genetic driving mutations are unknown. Herein, we present a case of this rare disease along with the results of molecular profiling via targeted next-generation sequencing. The patient is an 85-year-old man who presented with left eyelid swelling initially thought to be a chalazion. After no response to incision and drainage and antibiotics, an incisional biopsy was performed. Histopathologic sections revealed a proliferation of cells with signet-ring and histiocytoid morphology arranged singly and in cords infiltrating the dermis, subcutaneous tissue, and muscle. The lesional cells strongly expressed cytoplasmic cytokeratin 7 and nuclear androgen receptor. Next-generation sequencing revealed a CDH1 mutation, which is known to confer signet-ring morphology in other carcinomas. Pathogenic mutations in NTRK3, CDKN1B, and PIK3CA were also detected. To our knowledge, this is the first documented genetic analysis of this rare disease with findings that offer insights into disease pathogenesis and potential therapeutic targets.

Adipophilin expression in cutaneous malignant melanoma is associated with high proliferation and poor clinical prognosis

Adipophilin (ADP) is a primary protein component of lipid droplets (LDs). For more than half a century, certain types of cancer cells have been known to contain LDs in their cytoplasm. However, the pathological significance of ADP or LDs in cancer remains unclear. In the present study, we investigated the association between ADP and other pathological characteristics in cutaneous malignant melanomas to clarify the role of ADP in melanoma cells. We immunostained whole paraffin sections of primary cutaneous melanomas obtained from 90 cases for ADP, after which we analyzed the correlation between ADP immunohistochemistry (IHC) and patient survival data. We also studied the relationship between the ADP IHC score and in situ hybridization (ISH) score of ADP mRNA, and the Ki67-labeling index (Ki67-LI) by using tissue microarrays consisting of 74 primary cutaneous malignant melanomas, 19 metastasizing melanomas, and 29 melanocytic nevi. Finally, we analyzed the relationship between ADP expression and cell proliferation in cutaneous melanoma cell lines. We found that high ADP expression was associated with poor metastasis-free survival, disease-specific survival, and overall survival rates of patients with cutaneous melanomas (P < 0.05). By linear regression analysis, ADP IHC was correlated with increasing ADP mRNA ISH H-scores and Ki67-LI scores in melanocytic lesions (P < 0.01). ADP IHC and ADP ISH H-scores and Ki67-LI scores were greater in pT3-4 melanomas than in pT1-2 melanomas. In cell-based assays, cells with increased ADP expression showed higher proliferation rates compared with those of low-ADP cells. Thus, ADP expression in malignant melanoma was significantly associated with high cell proliferation and poor clinical prognosis. Our results thus indicate a significant association between ADP and melanoma progression, and we propose that ADP may be a novel marker of aggressive cutaneous melanoma with a lipogenic phenotype.

The Utility of Perilipin in Liposarcomas: PLIN1 Differentiates Round Cell Liposarcoma From Other Round Cell Sarcomas

Liposarcoma is the most common soft tissue sarcoma in adults; however, accurate diagnosis often depends on the use of ancillary molecular testing which can be time consuming and expensive. Myxoid/round cell liposarcoma may be a diagnostic challenge due to the morphologic similarities with other nonadipocytic sarcomas with round cell morphology. Immunohistochemistry may be a helpful adjunct to appropriately triage cases for molecular testing. Perilipin 1 (PLIN1) and perilipin 2 (adipophilin) (PLIN2) are intracellular proteins involved in lipid droplet formation, which we hypothesized may be useful as immunohistochemical markers for liposarcoma. Using archival tumor tissue, we assessed pattern of PLIN1 and PLIN2 expression in 46 adipocytic tumors and 36 nonadipocytic sarcomas. PLIN1 was expressed in 88% of liposarcomas, including 100% of myxoid/round cell liposarcomas, and did not have any expression in nonadipocytic sarcomas. PLIN1 was not expressed in dedifferentiated liposarcoma. Although PLIN2 demonstrates increased sensitivity for liposarcoma, including expression in dedifferentiated liposarcoma, it is not specific for adipocytic differentiation and is expressed in other nonadipocytic sarcomas. Furthermore, PLIN2 is not expressed in lipoma-like well-differentiated liposarcoma, and as such has limited diagnostic utility.

Lipid droplets: platforms with multiple functions in cancer hallmarks

Lipid droplets (also known as lipid bodies) are lipid-rich, cytoplasmic organelles that play important roles in cell signaling, lipid metabolism, membrane trafficking, and the production of inflammatory mediators. Lipid droplet biogenesis is a regulated process, and accumulation of these organelles within leukocytes, epithelial cells, hepatocytes, and other nonadipocyte cells is a frequently observed phenotype in several physiologic or pathogenic situations and is thoroughly described during inflammatory conditions. Moreover, in recent years, several studies have described an increase in intracellular lipid accumulation in different neoplastic processes, although it is not clear whether lipid droplet accumulation is directly involved in the establishment of these different types of malignancies. This review discusses current evidence related to the biogenesis, composition and functions of lipid droplets related to the hallmarks of cancer: inflammation, cell metabolism, increased proliferation, escape from cell death, and hypoxia. Moreover, the potential of lipid droplets as markers of disease and targets for novel anti-inflammatory and antineoplastic therapies will be discussed.

Spatial analysis of p63, K5 and K7 defines two groups of progenitor cells that differentially contribute to the maintenance of normal sebaceous glands, extraocular sebaceous carcinoma and benign sebaceous tumors

The histogenesis of extraocular sebaceous carcinomas is - in contrast to ocular sebaceous carcinomas - unclear, and information about the exact cellular architecture of these lesions and even of the normal sebaceous gland is still scarce. This study attempts to elucidate the histogenesis of sebaceous tumors, using multicolor immunofluorescence stainings to analyze 21 cases of sebaceous tumors (six each of extraocular sebaceous carcinoma, sebaceous adenoma and sebaceoma, and three cases of steatocystomas) and eight cases of normal sebaceous glands for p63, several keratins, androgen receptor, adipophilin, epithelial membrane antigen (EMA) and Ki-67. The data of this observational study provide evidence for the existence of two subpopulations of progenitors in normal sebaceous glands: (i) p63⁺ K5⁺ progenitors which generate the K10⁺ luminal cells of sebaceous ducts; and (ii) p63⁺ K5⁺ K7⁺ progenitors which finally generate K7⁺ adipophilin⁺ EMA⁺ sebocytes. Without exception, all types of sebaceous tumors contained p63⁺ K5⁺ cells. Furthermore, these tumors showed a cellular hierarchy and differentiation to adipophilin⁺ and/or EMA⁺ mature sebocytes and to K10⁺ ductal cells through intermediary cells. Notably, a considerable number of sebaceous tumors lack the K7 pathway of cell maintenance in the normal sebaceous lobule. Based on our data, we propose a cellular algorithmic model of the hierarchy of normal sebaceous glands and of sebocytic tumors in which p63⁺ K5⁺ cells play a major role.

Near complete response to Pembrolizumab in microsatellite-stable metastatic sebaceous carcinoma

BACKGROUND

Sebaceous carcinoma is an aggressive adnexal skin tumor with a predilection for the eyelids and sebaceous glands of the head and neck.

CASE PRESENTATION

A 73 year-old man presented with confusion and was found to have widely disseminated sebaceous carcinoma with metastases to brain, lungs, liver, bowel, lymph nodes, and bone. Following initial treatment of the brain metastases with surgery he received post-operative radiosurgery. He then began systemic immunotherapy with pembrolizumab. After 6 months, he developed a near complete response to therapy by irRECIST and RECIST v.1.1. The response was associated with circulating CD8+ T cells with central memory (CM) and effector memory (EM) phenotype and mature CD16 + CD57+ NK cells. During treatment the patient developed adrenal insufficiency requiring high-dose systemic corticosteroids and later adrenal replacement therapy. After 12-months of follow-up he showed imaging evidence of progression in liver, mediastinum, and abdominal lymph nodes. Given persistent, strong PD-L1 expression he resumed pembrolizumab therapy and showed radiographic evidence of an ongoing response to therapy.

CONCLUSIONS

This is the first report describing objective clinical and radiographic responses following immunotherapy for widely metastatic sebaceous carcinoma. The dramatic therapeutic response to pembrolizumab was associated with peripheral blood circulating memory T cells and mature Natural Killer cells after 6 months (24 weeks) of therapy. This report supports prospective clinical trials of anti-PD1 checkpoint blockade for metastatic sebaceous carcinoma.

Evaluation and comparison of staining patterns of factor XIIIa (AC-1A1), adipophilin and GATA3 in sebaceous neoplasia

BACKGROUND

Reliable nuclear immunohistochemical stains for sebaceous neoplasms have not been readily available. Positive nuclear staining has been reported for GATA3 and factor XIIIa (AC-1A1). We sought to determine the diagnostic utility of these nuclear stains by comparing their staining pattern to adipophilin, a consistently positive cytoplasmic stain.

METHODS

Cases with the diagnosis of sebaceous hyperplasia, sebaceous adenoma, sebaceous epithelioma/sebaceoma, sebaceous carcinoma, and nonsebaceous neoplasms (basal cell carcinoma and squamous cell carcinoma) were examined. Intensity and extent of staining of the basal cells and mature sebocytes were evaluated for each stain.

RESULTS

Factor XIIIa (AC-1A1) was 87.3% sensitive and 95.1% specific for all sebaceous neoplasms sand showed high inter-observer reliability. Adipophilin was 83.2% sensitive and 87.8% specific. GATA3 was the least sensitive (80.9%) and specific (75.6%) marker. When factor XIIIa was compared against composite staining of all three markers its staining was still uniquely significant (P = .0210).

CONCLUSION

Factor XIIIa (AC-1A1) is a sensitive and specific nuclear marker for sebaceous differentiation. Its diagnostic utility exceeds that of adipophilin. Factor XIIIa should be included in the expanding group of immunohistochemical and special stains which can be utilized to aid in the diagnosis of sebaceous neoplasms.

Sebaceous gland carcinoma of the ocular adnexa - variability in clinical and histological appearance with analysis of immunohistochemical staining patterns

PURPOSE

The purpose of the study was to evaluate the characteristics of sebaceous gland carcinoma (SGC) of the ocular adnexae, which is due to a high variability in clinical, histological and immunohistochemical characteristics often challenging to diagnose.

METHODS

Records of six patients with SGC were reviewed, who underwent surgical excision and who were histologically diagnosed with SGC. For comparison, there were specimens from four patients with basal cell carcinoma (BCC) and four patients with squamous cell carcinoma (SCC). Histological and immunohistochemical analysis included stains for HE, cytokeratins (CKpan, Cam5.2), epithelial membrane antigen (EMA), androgen receptor (AR441), perforin and adipophilin.

RESULTS

SGC's were located in the upper (n = 2) or lower (n = 4) eyelid and were associated with various presenting clinical signs including chalazion-like lesions with pyogenic granuloma (n = 1), papillomatous conjunctival tumors (n = 3), a hyperkeratotic exophytic neoplasm (n = 1) and an ulcerating crusted lesion resembling chronic blepharitis (n = 1). The treatment was tumor resection, followed (if necessary) by adjuvant therapy with topical Mitomycin C (n = 2). Histologic characteristics included basophilic pleomorphic cells with vacuolated cytoplasm, prominent nucleoli, mitotic figures and in some cases pagetoid spread (n = 2). CKpan, EMA and Cam5.2 showed strong positive immunoreactivity in all specimens (SGC, BCC, SCC). Perforin immunostaining showed a varying, but overall weak, non-specific cytoplasmatic staining reaction in all lesions. AR441 positivity was noted with variable intensity in almost all lesions and in particular in pagetoid spread in contrast to non-tumor cells. Adipophilin showed an annular staining of lipid granules in immature sebaceous cells in SGC in contrast to a more granular staining pattern in BCC and SCC.

CONCLUSION

SGCs display a variety of clinical signs and may mimic many other lesions. Tumor resection, followed by histological and immunohistochemical analysis, leads to the diagnosis and initiation of the proper treatment regimen. Herein, immunohistochemistry showed an unequivocal profile in SGC and did not allow for an exact differentiation from BCC and SCC by immunohistochemical means only. An extended evaluation of HE stains remains essential. However, immunohistochemistry can make relevant contributions to the diagnosis of SGC, especially in cases of inconclusive histology, by positive staining for adipophilin in immature sebaceous cells or by AR441 labeling in cases of pagetoid spread.

Sebaceous Carcinoma of the Eyelid

BACKGROUND

Periocular sebaceous carcinoma (PSC) is a rare but aggressive neoplasm that tends to clinically and histopathologically mimic other conditions. PSC can be challenging to diagnose using histomorphology alone given its overlap with 2 more common tumors that occur in this area (basal cell carcinoma [BCC] and squamous cell carcinoma [SCC]). Use of immunohistochemistry can help resolve this differential diagnosis.

METHODS

A review of the literature was performed, focusing on the epidemiology, morphology, and immunohistochemical features of PSC.

RESULTS

The most useful immunostains in the differential diagnosis of PSC are epithelial membrane antigen, Ber-Ep4, androgen receptor (AR), and adipophilin. To discern PSC from BCC, one should use EMA, Ber-Ep4, AR, and adipophilin, whereas discerning PSC from SCC can be achieved by evaluating AR and adipophilin. In addition, p53 and ERBB2 (formally known as HER2/neu) are other potentially useful immunohistochemical markers for the differential diagnosis of PSC.

CONCLUSIONS

Use of new immunohistochemical techniques, as well as the elucidation of molecular alterations, such as the presence of ERBB2 amplification, will advance our understanding of PSC.

Adipophilin expression in cutaneous malignant melanoma

BACKGROUND

The lipogenic pathway is upregulated in cancer cells, including melanomas. However, the pathological significance of cellular lipids in melanocytic lesions has yet to be determined. In this study, we evaluated intracytoplasmic lipid droplets in melanocytic nevi (MNs) and malignant melanomas via immunohistochemical analysis of adipophilin (ADP), which coats lipid droplets.

METHODS

One hundred primary cutaneous melanocytic lesions [33 MNs, 17 melanomas in situ (MIS), and 50 invasive melanomas (IMs)] were immunostained for ADP. The intensity score (IS) and proportion score (PS) of ADP staining in each case was recorded semiquantitatively on a scale of 0 to 3+.

RESULTS

High ADP expression (IS2/3+ and PS2/3+) was observed in 27 primary cutaneous melanocytic lesions that consisted of 23 IMs, three MISs, and one MN. Consequently, high ADP expression was associated with malignancy (38.8% vs. 3.0%; p < 0.0001). Among the IMs, high ADP expression was more prevalent in pT3/4 than pT1/2 (63.3% vs. 23.8%; p = 0.01) and Stage 3/4 than Stage 1/2 (76.9% vs. 36.8%; p = 0.02).

CONCLUSIONS

The majority of the melanocytic lesions with high ADP expression were malignant melanomas in our cohort. Therefore, ADP expression may serve as a sensitive diagnostic marker for malignant melanoma.

TERT promoter mutations in periocular carcinomas: implications of ultraviolet light in pathogenesis

BACKGROUND/AIMS

Ultraviolet light-signature mutations in the telomerase reverse transcriptase (TERT) gene promoter have been identified in cutaneous melanomas, basal cell carcinomas (BCCs), and squamous cell carcinomas (SCCs). Whether these mutations also occur in periocular tumours, including periocular sebaceous carcinomas (PSCs) and in situ tumours, has not been studied.

METHODS

DNA extraction, PCR and Sanger sequencing were used to determine the frequency of TERT promoter mutations in periocular tumours. The presence of mutations was correlated with histological evidence of solar elastosis.

RESULTS

Sixty-three tumours were analysed. TERT promoter mutations were identified in 18 of 22 BCCs (82%), 6 of 10 SCCs (60%), 1 of 2 in situ SCCs (50%), 4 of 9 grade III conjunctival intraepithelial neoplasia (CIN III) (44%) and 0 of 20 PSCs (0%). For BCCs, TERT promoter mutations were not associated with the histological risk categories of the tumours. For CIN III cases, all of the three lesions with solar elastosis had TERT promoter mutations, whereas the mutation was found in only one of the six CIN III cases without solar elastosis.

CONCLUSIONS

We demonstrate that ultraviolet light-signature TERT promoter mutations are very common in periocular BCCs, SCCs and CIN III lesions, indicating important roles of ultraviolet light in the pathogenesis of these tumours. In addition, the mutations are present in in situ stage. By contrast, no TERT promoter mutation is found in PSCs.

Clear cell proliferations of the skin

Clear cell proliferations of the skin consist of a diverse group of lesions characterized by the presence of cells with abundant clear cytoplasm. They may arise from primary, metastatic, or non-neoplastic origins, with their distinctive cytoplasmic clearing attributable to causes ranging from artifact to accumulation of materials such as glycogen, mucin, or lipids. Despite the heterogeneity of these lesions, their distinguishing characteristics may be subtle, especially at high power. As such, histologic diagnosis can be challenging, and proper consideration relies on an understanding of the scope of possible origins, etiologies, and key immunohistochemical staining patterns of the various entities. This review categorizes cutaneous clear cell neoplasms by histogenesis, and offers differential diagnostic strategies to aid in their clinicopathologic evaluation.

Immunohistochemistry in dermatopathology

CONTEXT

Immunohistochemistry is not a diagnostic test but a highly valuable tool that requires interpretation within a context.

OBJECTIVE

To review the current status and limitations of immunohistochemistry in dermatopathology.

DATA SOURCES

English-language literature published between 1980 and 2014.

CONCLUSIONS

Although immunohistochemistry is rarely completely specific or sensitive, it is an important adjunctive technique in dermatopathology and can be helpful in a series of diagnostic dilemmas.

[Differential diagnostics of sebaceous tumors]

Sebaceous tumors are epithelial tumors with a differentiation towards sebaceous adnexal structures of the skin. They imitate the epithelial cells of mature sebaceous glands, sebaceous ducts, immature (embryonic) sebaceous structures or sebaceous glands that are not stimulated by hormones (mantle structures). This article explains the classification of sebaceous tumors on the basis of the normal histology of sebaceous glands. Clinical and histopathological criteria are given for the most important sebaceous tumors. The differential diagnosis of sebaceoma, sebaceous adenoma and various types of sebaceous carcinoma is emphasized. The importance of a specific diagnosis of adnexal tumors is demonstrated by tumor-associated syndromes with involvement of other organs (e.g., Muir-Torre syndrome and Birt-Hogg-Dubé syndrome). Furthermore, conceptional controversies, problems in differential diagnosis and the impact of immunohistochemical staining in the assessment of sebaceous tumors are considered.

Eyelid sebaceous carcinoma: clinicopathologic and multiparametric immunohistochemical analysis that includes adipophilin

PURPOSE

To evaluate the fine cytopathologic features and immunohistochemistry of eyelid sebaceous carcinoma.

DESIGN

Retrospective clinicopathologic study.

METHODS

Clinical records and microscopic glass slides of 12 patients diagnosed with sebaceous carcinoma were reviewed. Paraffin-embedded tissue recuts were immunoreacted for epithelial membrane antigen (EMA), Ber-EP4, p53, Ki-67, and adipophilin for cytoplasmic lipid. Invasive growth and intraepithelial spread were analyzed separately. Cytoplasmic and nuclear characteristics were correlated with the results of the immunohistochemical profiling.

RESULTS

Five patients experienced recurrences, but no metastases or tumor-related deaths were discovered. The nuclei in 11 invasive tumor cells were typically round with finely divided, granular, or smudgy chromatin without prominent margination at the nuclear membrane; they exhibited small punctate nucleoli. Positivity for EMA (both diffuse and focal), p53 (72% of nuclei), and Ki-67 (45% proliferation index) was demonstrated. Adipophilin positivity in vesicular and granular forms was detected in paraffin sections in all invasive tumors, most prominently in moderately differentiated and well-differentiated lesions. Among 9 cases exhibiting intraepithelial extensions, 6 showed mostly granular positivity and 3 vesicular positivity. p53 identified residual atypical intraepithelial cells when conjunctival epithelial sloughing occurred.

CONCLUSIONS

Immunohistochemistry can make significant contributions to the diagnosis of sebaceous carcinoma. p53 and vesicular granular adipophilin positivity were highly reliable in supplementing the routine microscopic diagnosis of infiltrative tumors and both can be used in paraffin sections, thereby obviating cumbersome oil red O staining of frozen sections. The cells found in intraepithelial spread were strongly EMA and p53 positive, with more granular than vesicular adipophilin positivity.

Cutaneous and mammary apocrine carcinomas have different immunoprofiles

Often the distinction of cutaneous apocrine carcinoma from metastatic mammary apocrine carcinoma to the skin can be a diagnostic dilemma because both tumors share similar histologic features and have overlapping immunohistochemical profile. We compared the expression of adipophilin, cytokeratin 5/6, p63, GATA3, mammaglobin, androgen receptor, estrogen receptor, progesterone receptor, and HER2 by immunohistochemistry in 14 cutaneous apocrine carcinomas (11 primary tumors, 3 metastases) and 26 primary apocrine carcinomas of the breast. Whereas focal adipophilin staining was seen in 36% (5/14) of cutaneous apocrine carcinoma, strong and diffuse adipophilin staining was seen in 88% (22/25) of mammary apocrine carcinoma (P = .0013). Differences in estrogen receptor and progesterone receptor expression were also statistically significant (P = .018 and .043). Androgen receptor was strongly positive in all cutaneous and mammary cases. Although there was no significant difference in the frequency of expression of cytokeratin 5/6, p63, HER2, GATA3, and mammaglobin in cutaneous apocrine carcinoma versus mammary apocrine carcinoma, strong and diffuse cytokeratin 5/6 and/or mammaglobin expression were seen only in cutaneous apocrine carcinoma. In conclusion, cutaneous apocrine carcinoma is likely adipophilin- ER+ PR+/- HER2- and can exhibit strong and diffuse cytokeratin 5/6 and/or mammaglobin expression. On the contrary, a mammary apocrine carcinoma is likely adipophilin+ ER- PR- and often exhibit 3+ HER2 with corresponding HER2 gene amplification. A panel of adipophilin, ER, PR, HER2, cytokeratin 5/6, and mammaglobin may be helpful in distinguishing cutaneous apocrine carcinoma from mammary apocrine carcinoma.

Diagnostic utility of adipophilin immunostain in periocular carcinomas

PURPOSE

To determine the efficacy of adipophilin immunohistochemistry in the diagnosis of sebaceous carcinoma of the ocular adnexal region and to provide the guidelines for interpretation of this immunostain.

DESIGN

Retrospective, histopathologic case series.

PARTICIPANTS

A total of 25 patients with sebaceous carcinoma, 21 patients with basal cell carcinoma, 22 patients with conjunctival squamous cell carcinoma, 9 patients with cutaneous squamous cell carcinoma, and 5 patients with conjunctival mucoepidermoid carcinoma.

METHODS

Immunohistochemical staining for adipophilin was performed on paraffin-embedded tissues and correlated with hematoxylin-eosin, periodic acid-Schiff (PAS), and mucicarmine-stained preparations. Immunostaining was quantified by light microscopy and with a computerized image analysis system of scanned images. Statistical analysis was performed to compare immunostaining patterns within the tumor categories by stage and grade, between the different neoplasms, and for correlation between light microscopy observations and computerized image analysis.

MAIN OUTCOME MEASURES

Localization of adipophilin immunostain, intensity of immunostaining, percent of immunoreactive cells, percentages of vacuolar staining and granular staining, and vacuole size.

RESULTS

Adipophilin expression was observed in 100% of sebaceous carcinomas, 100% of cutaneous squamous cell carcinomas, 95% of basal cell carcinomas, 73% of conjunctival squamous cell carcinomas, and 60% of mucoepidermoid carcinomas. Sebaceous carcinomas demonstrated significantly stronger adipophilin expression, a greater number of intracytoplasmic vacuoles, and larger vacuoles. The specificity and sensitivity of adipophilin immunostaining in the diagnosis of sebaceous carcinoma were both 100% when more than 5% of the staining occurred in vacuoles (<95% granular staining). The diagnostic sensitivity and specificity were 100% and 96%, respectively, when the staining was graded as moderately or strongly intense and were 92% and 85% when the vacuoles were greater than 1.5 μm in diameter.

CONCLUSIONS

Although upregulation of neoplastic steatogenesis is observed in both sebaceous and nonsebaceous carcinomas, the pattern and intensity of adipophilin immunostaining are helpful in distinguishing sebaceous carcinoma from other neoplasms with overlapping histology.