Eccrine Porocarcinoma: New Insights and a Systematic Review of the Literature

Gene expression profiling in porocarcinoma indicates heterogeneous tumor development and substantiates poromas as precursor lesions

BACKGROUND AND OBJECTIVES

Malignant sweat gland tumors are rare, with the most common being eccrine porocarcinoma (EP). Approximately 18% of benign eccrine poroma (EPO) transit to EP. Previous research has provided first insights into the mutational landscape of EP. However, only few studies have performed gene expression analyses. This leaves a gap in the understanding of EP biology and potential drivers of malignant transformation from EPO to EP.

METHODS

Transcriptome profiling of 23 samples of primary EP and normal skin (NS). Findings from the EP samples were then tested in 17 samples of EPO.

RESULTS

Transcriptome profiling revealed diversity in gene expression and indicated biologically heterogeneous sub-entities as well as widespread gene downregulation in EP. Downregulated genes included CD74, NDGR1, SRRM2, CDC42, ANXA2, KFL9 and NOP53. Expression levels of CD74, NDGR1, SRRM2, ANXA2, and NOP53 showed a stepwise-reduction in expression from NS via EPO to EP, thus supporting the hypothesis that EPO represents a transitional state in EP development.

CONCLUSIONS

We demonstrated that EP is molecularly complex and that evolutionary trajectories correspond to tumor initiation and progression. Our results provide further evidence implicating the p53 axis and the EGFR pathway. Larger samples are warranted to confirm our findings.

Genexpressionsprofile beim Porokarzinom deuten auf heterogene Tumorentwicklung hin und untermauern Porome als Vorläuferläsionen

Hintergrund und Ziele

Maligne Schweißdrüsentumoren sind selten, wobei das ekkrine Porokarzinom (EP) das häufigste ist. Etwa 18 % der benignen ekkrinen Porome (EPO) entwickeln sich zum EP. Wissenschaftliche Studien haben erste Einblicke in die Mutationslandschaft von EPs geliefert. Allerdings wurden in nur wenigen Studien Genexpressionsanalysen durchgeführt. Dies hinterlässt eine Lücke im Verständnis der EP‐Biologie und potenzieller Treiber der malignen Transformation von EPO zu EP.

Methoden

Es wurde eine Transkriptomanalyse von 23 Proben primärer EP und normaler Haut (NH) durchgeführt. Die Ergebnisse aus den EP‐Proben wurden dann an 17 EP‐Proben getestet.

Ergebnisse

Das Transkriptom‐Profiling zeigte eine Vielfalt in der Genexpression und deutete auf biologisch heterogene Subeinheiten sowie eine weit verbreitete Herunterregulierung von Genen im EP hin. Herunterregulierte Gene umfassten CD74, NDGR1, SRRM2, CDC42, ANXA2, KFL9 und NOP53. Die Expressionsniveaus von CD74, NDGR1, SRRM2, ANXA2 und NOP53 zeigten eine stufenweise Abnahme der Expression von NH über EPO zu EP, was die Hypothese unterstützt, dass das EPO einen Zwischenschritt in der EP‐Entwicklung darstellt.

Schlussfolgerungen

Die Studie zeigt, dass das EP molekular komplex ist und der evolutionäre Verlauf der Tumorinitiierung und ‐progression entspricht. Die Ergebnisse legen eine Beteiligung der p53‐Achse und des EGFR‐Signalwegs nahe. Eine größere Probenanzahl ist erforderlich, um diese Ergebnisse zu bestätigen.

Adnexal neoplasms of the eye

Adnexal neoplasms of the eyelid encompass a wide variety of benign and malignant tumors of sebaceous, follicular, and sweat gland origin. Due to the specialized structures of the eyelid, these neoplasms present differently when compared with those of other locations. Although most dermatologists and ophthalmologists are familiar with the commonly reported adnexal tumors of the eyelid, such as hidrocystoma, pilomatrixoma, and sebaceous carcinoma, many other adnexal neoplasms have been reported at this unique anatomic site. Accurate and timely identification of these neoplasms is essential, as alterations of eyelid anatomy and function can have a negative impact on eye health, vision, and quality of life. We review the clinical and histopathologic features of common and rare eyelid adnexal neoplasms and discuss proposed treatment options.

Porocarcinoma: Clinical and Histological Features, Immunohistochemistry and Outcomes: A Systematic Review

Porocarcinoma (PC) is a rare adnexal tumor, mainly found in the elderly. The tumor arises from the acrosyringium of eccrine sweat glands. The risk of lymph node and distant metastasis is high. Differential diagnosis with squamous cell carcinoma is difficult, although NUT expression and YAP1 fusion products can be very useful for diagnosis. Currently, wide local excision is the main surgical treatment, although Mohs micrographic surgery is promising. To date, there is no consensus regarding the role of sentinel lymph node biopsy and consequential lymph node dissection. No guidelines exist for radiotherapy, which is mostly performed based on tumor characteristics and excision margins. Only a few studies report systemic treatment for advanced PC, although therapy with pembrolizumab and EGFR inhibitors show promise. In this review, we discuss epidemiology, clinical features, histopathological features, immunohistochemistry and fusion products, surgical management and survival outcomes according to stage, surgical management, radiotherapy and systemic therapy.

Navigating Head and Neck Porocarcinoma: Systematic Review with Special Emphasis on Surgical Safety Margins

Eccrine porocarcinoma, sharing many features with other skin tumours, is diagnostically challenging. A conventional biopsy might be misleading and surgical excision becomes a primary diagnostic tool and a treatment method. However, the data on surgical safety margins are not consistent. We present a systematic review analysing the surgical margins of porocarcinoma in the head and neck area, which was conducted across the PubMed, Cochrane, and Web of Science databases including studies published from inception to November of 2023. In this systematic review, the PRISMA-ScR checklist was used, and a Cohen's Kappa coefficient of 0.92 was applied, indicating very good agreement between reviewers. Out of 529 identified articles, 18 studies yielding 20 cases in total were selected for a thorough analysis. Nine (45%) cases were observed in the facial regions, eight (40%) on the scalp, and three (5%) on the neck. The primary treatment of choice was wide local excision with safety margins ranging from 3 to 22 mm (mean: 10.1). It demonstrated that surgical margins do not differ by age or anatomic regions, with the main point of reference being the tumour size. As observed, the bigger the tumour, the wider the safety margins were. However, the limited disclosure of surgical safety margins in analysed case reports impeded our ability to define the minimum safety margins. Further investigation and a consensus on recommended safety margins are required.

Spindle cell porocarcinoma with a novel YAP1::MAML3 fusion

Porocarcinomas are rare sweat gland cancers representing the malignant counterpart to benign poromas. Their diagnosis can be challenging, especially in the absence of an associated poroma or when the tumor is poorly differentiated. Since recurrent YAP1::MAML2 and YAP1::NUTM1 fusions have been identified in poroid tumors, molecular studies provide an opportunity to support the diagnosis in challenging cases. We describe a case of a female patient in her early 90s, with a polypoid mass of the hip. Histopathologically, there was a poorly differentiated malignant spindle cell tumor adjacent to a poroma. Because of the close association with a poroma and immunoreactivity for p40, a diagnosis of spindle cell porocarcinoma was rendered, which was further supported by YAP1 immunohistochemical studies. Antibodies targeting both the N-terminus and C-terminus confirmed YAP1 rearrangement in both the poroma and the spindle cell neoplasm. Subsequent targeted RNA sequencing revealed a YAP1::MAML3 gene fusion. MAML3 has previously not yet been reported as a YAP1 fusion partner in porocarcinoma. With the illustration of a rare spindle cell variant of porocarcinoma and the identification of a novel gene fusion, this case report expands the spectrum of morphologic and genomic aberrations associated with porocarcinoma.

Porocarcinoma in a palm reconstructed with a full thickness skin graft: A case report

BACKGROUND

Porocarcinoma is a rare type of skin cancer that originates from sweat gland tumors. It is an aggressive malignant skin cancer that is difficult to diagnose clinically owing to its rarity and similarity to squamous cell carcinoma (SCC).

CASE SUMMARY

This case involved a 92-year-old woman, a farmer by profession, presented with an exophytic and verrucous mass on her left palm that had formed 2 years prior and caused chronic pain and frequent bleeding. Initially, the patient was diagnosed with SCC using a punch biopsy; however, a repeat biopsy with additional immunohistochemical tests was performed for porocarcinoma. Ultimately, the patient was diagnosed with porocarcinoma and reconstruction was planned using a full-thickness skin graft. After treatment, the range of motion of the palm was preserved, and the aesthetic outcome was favorable. At 6 mo of follow-up, the patient was satisfied with the outcome.

CONCLUSION

Porocarcinoma is commonly misdiagnosed as SCC; therefore, clinicians should consider porocarcinomas when evaluating mass-like lesions on the hands.

Gene fusions in poroma, porocarcinoma and related adnexal skin tumours: An update

Poroma is a benign sweat gland tumour showing morphological features recapitulating the superficial portion of the eccrine sweat coil. A subset of poromas may transform into porocarcinoma, its malignant counterpart. Poroma and porocarcinoma are characterised by recurrent gene fusions involving YAP1, a transcriptional co-activator, which is controlled by the Hippo signalling pathway. The fusion genes frequently involve MAML2 and NUTM1, which are also rearranged in other cutaneous and extracutaneous neoplasms. We aimed to review the clinical, morphological and molecular features of this category of adnexal neoplasms with a special focus upon emerging differential diagnoses, and discuss how their systematic molecular characterisation may contribute to a standardisation of diagnosis, more accurate classification and, ultimately, refinement of their prognosis and therapeutic modalities.

Eccrine Porocarcinoma of the Vulva With Sarcomatoid Transformation, a New Human Papillomavirus-associated Malignancy? Case Report and Review of the Literature

Eccrine porocarcinoma is a rare cutaneous neoplasm, and rarer still in the anogenital region. In the vulva, the most common carcinoma by far is squamous cell carcinoma; however, eccrine porocarcinoma can arise at this site. As the distinction between porocarcinoma and squamous cell carcinoma has important prognostic implications at other cutaneous sites, it stands to reason that it may have these same implications in the vulva. We present a case of an eccrine porocarcinoma in the vulva of a 70-year-old woman that, in addition, showed sarcomatoid transformation. This tumor harbored human papillomavirus-18 DNA and mRNA, raising the question of the role of the oncogenic virus in sweat gland neoplasms of the vulva.

Primary groin porocarcinoma in a 43-year-old man successfully managed by local excision: A case report and literature review

Porocarcinoma is a rare skin malignancy that should be suspected in patients with chronic skin lesions. Although it usually affects the elderly population in sun-exposed areas, it may be seen in younger populations and in nonexposed areas such as the groin.

Porocarcinoma Concurrent with Psoriasis Vulgaris: The First Report

Psoriasis is a common chronical inflammatory skin disease with a prevalence of 2%-4% worldwide. In contrast, porocarcinoma is a relatively rare cutaneous neoplasm and an associated localization of both lesions is rare. Here, we describe the first case of porocarcinoma in a patient with psoriasis. A 71-year-old Japanese man was referred to our clinic for evaluation of nodule within a keratotic plaque of 20-years history on his leg. Histopathological examination showed that the plaque revealed acanthosis with regular elongation of rete ridges, agranulosis and the presence of Munro microabscesses. In contrast, massive proliferation of atypical poroid cells and a few cuticular cells in the dermis were seen in the nodule. We speculated that it is likely the porocarcinoma was caused by the elevated risk of skin cancer due to chronic inflammatory process of psoriasis itself in our patient.

Eccrine Porocarcinoma: Clinical and Histopathological Study of 14 Patients with Special Emphasis on Sentinel Lymph Node Biopsy

Eccrine porocarcinoma is a rare skin adnexal tumour that affects elderly people. Most eccrine porocarcinomas are stage I or II according to the American Joint Committee on Cancer. The prognosis is good in early stages, but worsens when advanced. Since information on the use of sentinel lymph node biopsy in these patients is scarce, this study examined the records of all patients with eccrine porocarcinoma treated at Helsinki University Hospital during a 17-year period and focused on sentinel lymph node biopsy patients. The study identified 14 patients (9 male, 5 female). There were 2 metastases to the lymph nodes and 2 recurrences at initial referral to our institution. All primary tumours had wide local excision and 6 patients also had sentinel lymph node biopsy, of whom none had positive lymph nodes. There were no new metastases or recurrences during follow-up. Three patients died of causes other than eccrine porocarcinoma. When comparing the wide local excision only and wide local excision with sentinel lymph node biopsy groups, no parameters reached statistical significance. The decision process of the multidisciplinary tumour board meeting on whether to perform sentinel lymph node biopsy was not clear, perhaps due to the limited knowledge of eccrine porocarcinoma. Further studies and international collaboration are warranted.

Epidemiology of porocarcinoma in England 2013-2018: a population-based registry study

BACKGROUND

Porocarcinoma (PC) is a cutaneous malignancy that differentiates towards (possibly arises from) the sweat ducts and glands. Lack of histological diagnostic markers makes clinical and pathological diagnosis complex. The limited data available suggest the incidence is increasing; however, this remains to be established in national epidemiological studies.

OBJECTIVES

To report the incidence, treatment and survival of patients with PC in England from 1 January 2013 to 31 December 2018 using national cancer registry data.

METHODS

PC diagnoses in England during 2013-2018 were identified from the National Disease Registration Service using morphology and behaviour codes. These were registered from routinely collected pathology reports and cancer outcomes and services datasets. The 2013 European age standardized incidence rates (EASRs), Kaplan-Meier all-cause survival and log-rank test were calculated.

RESULTS

In total, 738 tumours (396 in males and 342 in females) were diagnosed. The median age at diagnosis was 82 years old (interquartile range 74-88). The most frequently affected site were lower limbs (35.4%), followed by the face (16%). The majority of the cohort received surgical excision (73.0%). The Kaplan-Meier all-cause survival was 45.4% at 5 years, which was lower than in previous studies. The EASR for the whole population was 0.25 [95% confidence interval (CI) 0.23-0.27] per 100 000 person-years (PY)]. PC incidence rates in the East of England (EASR of 0.54, 95% CI 0.47-0.63 per 100 000 PY) were three times higher than the South West (EASR of 0.14, 95% CI 0.10-0.19 per 100 000 PY) where the regional rates were the lowest.

CONCLUSIONS

This study shows that there is large variation in the EASRs of PC across England. This may reflect differences in how PC is diagnosed and registered in different regions in England. These data support national assessment of the management of PC, which will inform future studies and guideline development.

Eccrine Porocarcinoma: A Review of the Literature

Eccrine porocarcinoma (EPC) constitutes a rare malignant adnexal tumor, which accounts for about 0.005-0.01% of all cutaneous malignancies. It may develop de novo or arise from an eccrine poroma, after a latency period of years or even decades. Accumulating data suggest that specific oncogenic drivers and signaling pathways may be implicated in its tumorigenesis, while recent data have demonstrated a high overall mutation rate attributed to UV exposure. Diagnosis may be challenging and should rely on the combination of clinical, dermoscopical, histopathological and immunohistochemical findings. The literature is controversial regarding tumor behavior and prognosis and, therefore, there is no consensus on its surgical management, utility of lymph-node biopsy and further adjuvant or systemic treatment. However, recent advances in tumorigenesis of EPC may aid in the development of novel treatment strategies, which could improve survival of advanced or metastatic disease, such as immunotherapy. This review presents an update of the epidemiology, pathogenesis and clinical presentation of EPC and summarizes current data on diagnostic evaluation and management of this rare cutaneous malignancy.

Eccrine Porocarcinoma of Dorsum of Nose: A Rare Case Report

Eccrine porocarcinoma (EPC) is an uncommon malignant tumor derived from the eccrine sweat glands. Because of its various pathological features, it is often confused with other malignant cutaneous tumors. We present a case of 78-year- old female having ulcerative lesion over external nasal pyramid. Biopsy suggested of squamous cell carcinoma. Tumor was excised and reconstruction was done using paramedian forehead flap. Post operative Histopathological Examination (HPE) suggested of eccrine porocarcinoma.

An Unusual Case of a Scrotal Porocarcinoma and Review of the Literature

ABSTRACT

Porocarcinomas are rare tumors derived from the acrosyringium and eccrine ducts, which most commonly occur on the lower extremities or head and neck region in older adults. Microscopically, they invariably demonstrate continuity with the epithelium, showing downgrowth of broad anastomosing bands with more infiltrative intradermal cords and nests of pleomorphic tumor cells with ductal lumina; an associated poroma may also be seen. We report an unusual case of a porocarcinoma arising on the scrotum of a 55-year-old man. Because of the extraordinary location and the presence of keratinizing squamous differentiation, distinction from a squamous cell carcinoma was particularly challenging. Close examination revealed the presence of a co-existing poroma, and immunohistochemistry revealed loss of YAP1 with diffuse nuclear expression of NUT in both the porocarcinoma and poroma components. This finding is particularly suggestive of a YAP1::NUTM1 fusion which has been reported to be highly specific for poroid neoplasms. Distinction of porocarcinoma from its mimics is important due to the frequent aggressive behavior of this neoplasm.

Intraabdominal dissemination of porocarcinoma; A case report

Introduction

Porocarcinoma is a rare malignancy of dermal sweat glands commonly diagnosed in the seventh decade of life. It frequently evolves from a de novo benign poroma. These tumors present as a mass/nodule, ulcer, papule, or wart. Difficult to differentiate from other cutaneous lesions. Intraperitoneal invasion is scantly reported in the literature.

Case presentation

The authors present a case of a fifty-year-old female patient with a rare cancer of the dermal sweat glands in an unusual location and infiltration into the abdominal cavity, leading to intraperitoneal seedlings.

Discussion

Tumors of the sweat gland are rare and difficult to diagnose, often misdiagnosed as granuloma, squamous cell tumors, or warts. Surgical excision and Mohs micrographic surgery are mainstay treatment modalities in the early stages. Our patient was managed elsewhere with a diagnosis of granuloma. She was referred with a recurrence of the abdominal lesion. An appropriate diagnosis of porocarcinoma was made while she had an extensive intraperitoneal invasion and seedlings. We postulate that the previous abdominal incision had disseminated porocarcinoma cells into the abdominal cavity, causing extensive intraperitoneal dissemination.

Conclusion

Because it is rare and difficult to diagnose, there is a considerable knowledge gap in the early accurate diagnosis and appropriate management of porocarcinoma. This causes a delay in establishing a diagnosis and profoundly impacts treatment outcomes.

•

Eccrine porocarcinoma is a rare diagnosis of cutaneous malignancy.

•

Early diagnosis and appropriate surgical treatment are the cornerstones of improving survival.

•

It is often misdiagnosed as granuloma, squamous cell carcinoma, or viral warts.

YAP1-NUTM1 Gene Fusion in Eccrine Porocarcinoma with Late Metastatic Recurrence: A Case Report

Abstract is missing (Short communication)

Primary Eccrine Porocarcinoma of the Breast: A Case Report and Review of Literature

Eccrine porocarcinoma (EPC) is a rare cutaneous neoplasm, with less than 500 reported cases worldwide since it was first described in 1963. EPC tends to affect the elderly and most commonly affects the head and neck. The mainstay of EPC treatment is surgery, with lymphadenectomy in the case of nodal involvement or presence of unfavourable characteristics. No evidence exists to guide the use of adjuvant chemotherapy or radiation. EPC is prone to misdiagnosis given its multiple clinical and histopathological mimics, especially in uncommon sites of presentation such as the breast. Herein, we report the case of a 59-year-old woman who presented with a left breast skin lump. The biopsied specimen revealed an infiltrative carcinoma involving the dermis and epidermis with positive IHC staining for P63 and CK5/6 and negative staining for ER, PR, and HER2. The tumour was resected and diagnosed as EPC with atypical features as overlapping characteristics of squamous cell carcinoma (SCC) were detected on histopathological analysis. In our case, a simple mastectomy with broad margins and axillary lymph node dissection with adjuvant radiotherapy to a dose of 60 Gy failed to achieve loco-regional control with nodal recurrence occurring 4 months postsurgery-a testament to the aggressive course of this rare malignancy.

Porocarcinoma of the left arm: A report of a rare skin cancer case and literature review

Porocarcinoma is a rare type of skin cancer that develops from the intraepidermal ductal part of eccrine sweat glands. It can arise de novo or from poroma ground with high potential for locoregional metastatic spread, morbidity, and mortality. It mostly occurs in elderly patients.

Head and Neck Porocarcinoma: SEER Analysis of Epidemiology and Survival

Porocarcinoma is a rare malignant adnexal tumor. Little is known about the location of the disease in the head and neck. Our aim is to offer the largest analysis of demographic, pathological, and treatment patterns of head and neck porocarcinoma in comparison with other locations of the neoplasm from an epidemiologically representative cohort. Method: The Surveillance, Epidemiology, and End Results program of the National Cancer Institute was searched for all cases of porocarcinomas diagnosed between 2000 and 2018. This database is considered representative of the US population. Demographic, pathological, and treatment variables were compared between the head and neck and other regions. Overall and disease-specific survival was calculated and compared between groups. Results: 563 porocarcinomas were identified, with 172 in the head and neck. The mean age was 66.4 years. Males were more affected in the head and neck. Regional and distant invasion rates were low (2.9 and 2.3%, respectively). Local excision and Mohs surgery were the most frequent therapies. Five-year overall survival was 74.8%. Five-year disease-specific survival was 97%. Conclusions: Head and neck porocarcinoma affects more males than females. Regional or distant metastatic rates are low and overestimated in previous literature. Disease-specific mortality is low. Surgery remains the mainstay of treatment.

UV-induced local immunosuppression in the tumour microenvironment of eccrine porocarcinoma and poroma

Eccrine porocarcinoma (EPC) is a rare malignant adnexal tumour of the skin. Part of EPCs develop from their benign counterpart, poroma (EP), with chronic light exposure and immunosuppression hypothesized to play a role in the malignant transformation. However, the impact of chronic light exposure on the microenvironment of EPCs and EPs has not been investigated yet. Although the clinical relevance of tumour infiltrating lymphocytes (TILs) and tertiary lymphoid structures (TLSs) has been established in various tumours, their distribution and significance in EPCs and EPs is still poorly understood. We characterized the distribution of TILs and TLSs using CD3, CD4, CD8, CD20 immunohistochemistry in a cohort of 10 EPCs and 49 EPs. We then classified our samples using solar-elastosis grading, analyzing the influence of ultraviolet (UV) damage on TIL density. A negative correlation between UV damage and TIL density was observed (CD4 r = −0.286, p = 0.04. CD8 r = −0.305, p = 0.033). No significant difference in TIL density was found between EPCs and EPs. TLS was scarse with the presence rate 10% in EPCs and 8.3% in EPs. The results suggest that UV has an immunosuppressive effect on the microenvironment of EPCs and EPs.

Porocarcinoma: an epidemiological, clinical, and dermoscopic 20-year study

BACKGROUND

Porocarcinoma (PC) is a rare cutaneous adnexal tumor with a variable metastatic potential. Given the paucity of data, guidelines and specific recommendations for PC are not yet well-established. In this study, we evaluate the disease-specific characteristics and outcome of this rare and often underestimated tumor.

MATERIALS AND METHOD

A retrospective study of the epidemiological, clinical, and dermoscopic characteristics among cases of histopathologically diagnosed PC, collected from the database of two skin cancer clinics in Italy (Firenze, Pistoia) from 2000 to 2020, was conducted.

RESULTS

Among the 52 patients with 53 tumors, 31 were men (59.6%) and 21 were women (40.4%) with an age range of 49-96 years (median age 82 years). The most common locations were the head/neck region in men (34% in men vs. 17% in women) and the lower limb in women (17% in women vs. 9% in men). Forty-eight cases (91%) underwent local excision. Of these patients, two (4%) experienced local recurrence, and one (2%) developed a second PC on a different anatomical site 1 month after the primary tumor's excision. Lymph node metastases were present in three cases (6%). Two of them have been treated surgically with adjuvant radiotherapy (both are disease-free after a 2-year follow-up period), whereas the third case developed visceral metastases followed by PC-related death.

CONCLUSIONS

This study, with 52 patients with 53 tumors covering a follow-up period of more than 5 years, shows a less aggressive behavior of PC with 4% local recurrence, 6% nodal metastases, and 2% mortality.

Molecular pathology of skin adnexal tumours

AIMS

Tumours of the cutaneous adnexa arise from, or differentiate towards, structures in normal skin such as hair follicles, sweat ducts/glands, sebaceous glands or a combination of these elements. This class of neoplasms includes benign tumours and highly aggressive carcinomas. Adnexal tumours often present as solitary sporadic lesions, but can herald the presence of an inherited tumour syndrome such as Muir-Torre syndrome, Cowden syndrome or CYLD cutaneous syndrome. In contrast to squamous cell carcinoma and basal cell carcinoma, molecular changes in adnexal neoplasia have been poorly characterised and there are few published reviews on the current state of knowledge.

METHODS AND RESULTS

We reviewed findings in peer-reviewed literature on molecular investigations of cutaneous adnexal tumours published to June 2021.

CONCLUSIONS

Recent discoveries have revealed diverse oncogenic drivers and tumour suppressor alterations in this class of tumours, implicating pathways including Ras/MAPK, PI3K, YAP/TAZ, beta-catenin and nuclear factor kappa B (NF-κB). These observations have identified novel markers, such as NUT for poroma and porocarcinoma and PLAG1 for mixed tumours. Here, we provide a comprehensive overview and update of the molecular findings associated with adnexal tumours of the skin.

Whole-exome sequencing in eccrine porocarcinoma indicates promising therapeutic strategies

Malignant sweat gland tumours are rare, with the most common form being Eccrine porocarcinoma (EP). To investigate the mutational landscape of EP, we performed whole-exome sequencing (WES) on 14 formalin-fixed paraffin-embedded samples of matched primary EP and healthy surrounding tissue. Mutational profiling revealed a high overall median mutation rate. This was attributed to signatures of mutational processes related to ultraviolet (UV) exposure, APOBEC enzyme dysregulation, and defective homologous double-strand break repair. All of these processes cause genomic instability and are implicated in carcinogenesis. Recurrent driving somatic alterations were detected in the EP candidate drivers TP53, FAT2, CACNA1S, and KMT2D. The analyses also identified copy number alterations and recurrent gains and losses in several chromosomal regions including that containing BRCA2, as well as deleterious alterations in multiple HRR components. In accordance with this reduced or even a complete loss of BRCA2 protein expression was detected in 50% of the investigated EP tumours. Our results implicate crucial oncogenic driver pathways and suggest that defective homologous double-strand break repair and the p53 pathway are involved in EP aetiology. Targeting of the p53 axis and PARP inhibition, and/or immunotherapy may represent promising treatment strategies.

Unusual Presentations of Eccrine Porocarcinomas

Eccrine porocarcinomas (EPCs) are rare tumours, albeit the most common malignant adnexal tumours of the skin. They can present with very heterogeneous clinical and dermoscopic features, rendering diagnosis limited to histopathological examination alone. We share 2 cases of EPCs, one of which arose in a patient with a prior diagnosis of cutaneous squamous cell carcinoma (SCC) and another whose EPC was likely a malignant transformation of an existing poroma. An occurrence of porocarcinoma after the diagnosis of SCC may suggest the possibility of unknown risk factors for both. Positivity to androgen, oestrogen, and epidermal growth factor receptors was seen in a proportion of porocarcinomas, and this may prompt further research on combination therapy between conventional treatment modalities with hormone receptor antagonists. Malignant change of a poroma may be a more common phenomenon than we would expect based on the current literature.

Merkel cell polyomavirus is a passenger virus in both poroma and porocarcinoma

BACKGROUND

Merkel cell polyomavirus (MCPyV) has been studied in several malignant and nonmalignant tissues. However, only in Merkel cell carcinoma (MCC) has the connection to tumorigenesis been established. Previously, eccrine porocarcinoma samples were shown to express MCPyV in the majority of samples. We aimed to examine MCPyV in porocarcinoma and poroma samples using MCC as the reference material.

METHODS

We analyzed 17 porocarcinoma and 50 poroma samples for the presence of MCPyV using LT antigen immunostaining and DNA detection methods. In addition, 180 MCC samples served as controls.

RESULTS

MCPyV LT antigen immunostaining was detected in 10% of poroma and 18% of porocarcinoma samples; on the other hand, it was present in 65% of MCC samples. MCPyV DNA was detected in only 10% of poroma and porocarcinoma samples compared with 96% of MCC samples. The viral DNA copy number in all MCPyV DNA-positive MCCs was at least 25 times higher than that in porocarcinoma or poroma samples with the highest MCPyV DNA-to-PTPRG ratio.

CONCLUSIONS

The low number of viral DNA copies in poroma and porocarcinoma samples, together with the negative LT expression of MCPyV DNA-positive tumors, indicates that MCPyV is simply a passenger virus rather than an oncogenic driver of porocarcinoma.

High tumour mutational burden and EGFR/MAPK pathway activation are therapeutic targets in metastatic porocarcinoma

BACKGROUND

Eccrine porocarcinoma (EPC) is a rare skin cancer arising from the eccrine sweat glands. Due to the lack of effective therapies, metastasis is associated with a high mortality rate.

OBJECTIVES

To investigate the drivers of EPC progression.

METHODS

We carried out genomic and transcriptomic profiling of metastatic EPC (mEPC), validation of the observed alterations in an EPC patient-derived cell line, confirmation of relevant observations in a large patient cohort of 30 tumour tissues, and successful treatment of a patient with mEPC under the identified treatment regimens.

RESULTS

mEPC was characterized by a high tumour mutational burden (TMB) with an ultraviolet signature, widespread copy number alterations and gene expression changes that affected cancer-relevant cellular processes such as cell cycle regulation and proliferation, including a pathogenic TP53 (tumour protein 53) mutation, a copy number deletion in the CDKN2A (cyclin dependent kinase inhibitor 2A) region and a CTNND1/PAK1 [catenin delta 1/p21 (RAC1) activated kinase 1] gene fusion. The overexpression of EGFR (epidermal growth factor receptor), PAK1 and MAP2K1 (mitogen-activated protein kinase kinase 1; also known as MEK1) genes translated into strong protein expression and respective pathway activation in the tumour tissue. Furthermore, a patient-derived cell line was sensitive to EGFR and MEK inhibition, confirming the functional relevance of the pathway activation. Immunohistochemistry analyses in a large patient cohort showed the relevance of the observed changes to the pathogenesis of EPC. Our results indicate that mEPC should respond to immune or kinase inhibitor therapy. Indeed, the advanced disease of our index patient was controlled by EGFR-directed therapy and immune checkpoint inhibition for more than 2 years.

CONCLUSIONS

Molecular profiling demonstrated high TMB and EGFR/MAPK pathway activation to be novel therapeutic targets in mEPC.

[Management of malignant adnexal neoplasms of the skin]

Malignant adnexal neoplasms of the skin are a heterogeneous group of rare malignancies with eccrine, apocrine, sebaceous and follicular differentiation. Essential clinical practice recommendations for the overall management of these cancers are presented. Moreover, specific evidence-based findings according to diagnosis, therapy and follow-up of porocarcinoma, sebaceous carcinoma and microcystic adnexcarcinoma will be explained.

Update on Molecular Genetic Alterations of Cutaneous Adnexal Neoplasms

Cutaneous adnexal tumors recapitulate follicular, sweat gland, and/or sebaceous epithelia, and range from benign tumors to aggressive carcinomas. Adnexal tumors can be hallmarks for inherited tumor syndromes. Oncogenic drivers of adnexal neoplasms modulate intracellular pathways including mitogen-activated protein kinase, phosphoinositide-3-kinase, Wnt/β-catenin, Hedgehog, nuclear factor κB, and Hippo intracellular signaling pathways, representing potential therapeutic targets. Malignant progression can be associated with tumor suppressor loss, especially TP53. Molecular alterations drive expression of specific diagnostic markers, such as CDX2 and LEF1 in pilomatricomas/pilomatrical carcinomas, and NUT in poromas/porocarcinomas. In these ways, improved understanding of molecular alterations promises to advance diagnostic, prognostic, and therapeutic possibilities for adnexal tumors.

Current Diagnosis and Treatment Options for Cutaneous Adnexal Neoplasms with Apocrine and Eccrine Differentiation

Adnexal tumors of the skin are a rare group of benign and malignant neoplasms that exhibit morphological differentiation toward one or more of the adnexal epithelium types present in normal skin. Tumors deriving from apocrine or eccrine glands are highly heterogeneous and represent various histological entities. Macroscopic and dermatoscopic features of these tumors are unspecific; therefore, a specialized pathological examination is required to correctly diagnose patients. Limited treatment guidelines of adnexal tumor cases are available; thus, therapy is still challenging. Patients should be referred to high-volume skin cancer centers to receive an appropriate multidisciplinary treatment, affecting their outcome. The purpose of this review is to summarize currently available data on pathogenesis, diagnosis, and treatment approach for apocrine and eccrine tumors.

Eccrine Porocarcinoma: A Challenging Diagnostic and Therapeutic Tumoral Entity

Eccrine porocarcinoma is a rare malignant cutaneous tumor with high rates of extracutaneous spread, and its diagnosis and management can be quite challenging. This is a case of an 82-year-old woman presenting with an asymptomatic and chronic pubic skin lesion for whom the work-up required many investigations and procedures to confirm the diagnosis of metastatic eccrine porocarcinoma. Indeed, the patient underwent a wide local excision of the skin lesion, imaging with an FDG-PET scan, a colonoscopy, and two inguinal node dissections. As illustrated in this case, surgery should always be considered to achieve disease remission. Other treatments such as chemotherapy and radiotherapy have also been reported in the literature without clear standard guidelines.

Basal Cell Carcinoma and Eccrine Porocarcinoma of the Eyelid

An 81-year-old woman presented with a progressively enlarging indurated, firm lesion encompassing one-third of the left upper eyelid. Four years prior, a similar lesion at that same site had been excised and diagnosed as a basal cell carcinoma. The patient underwent a full-thickness excision of the lesion with frozen section, cryotherapy, and reconstruction. A free tarsal graft and hard palate composite graft was used to reconstruct the posterior lamella. A Mustarde myocutaneous rotational flap was used to reconstruct the anterior lamella. Histopathology illustrated nests of pleomorphic basophilic cells with varying mitotic activity and immunohistochemical staining consistent with eccrine porocarcinoma. This case highlights similarities in the presentation and appearance of basal cell carcinoma and periorbital eccrine porocarcinoma. It is possible that there was de novo development of the 2 tumors on the eyelid or recurrence of a misdiagnosed eccrine porocarcinoma. Eccrine porocarcinomas are rare malignant sweat gland tumors associated with a risk of recurrence after excision and metastasis.

Clear Cell Differentiation in Eccrine Porocarcinoma as a High-Risk Feature: Epidemiologic and Pathologic Features of Eccrine Porocarcinoma in a Single-Center Case Series

ABSTRACT

Eccrine porocarcinoma (EPC) is a rare sweat gland malignancy. Recognition of histologic features is challenging, and specific pathologic features correlate with risk of poor outcome. This single-center retrospective review and case series of 58 EPC cases from 2000 to 2016 elucidates epidemiologic and pathologic characteristics of EPC. Pathology slides from 52 cases were analyzed by a dermatopathologist for standardized variable characteristics, including previously determined high-risk features (HRF) associated with poor prognosis. The incidence of EPC increased over the study period with 3 times more cases diagnosed in the last 4 years than in the first 4 years. Most cases were in the elderly males (mean age 75 years), and 50% were located in the head and neck region. Although 38% of tumors exhibited one histologic HRF, only 10% exhibited more than one. Of the HRF, a greater tumor depth was associated with both increased age (P = 0.04) and clear cell differentiation (P = 0.02). This study elucidates epidemiologic and pathologic features of EPC and highlights how age and clear cell differentiation can be associated with greater tumor depth, although further research is needed to determine whether clear cell differentiation is associated with poor clinical outcome.

Malignant Cutaneous Adnexal Tumors and Role of SLNB

BACKGROUND

Malignant cutaneous adnexal tumors (MCATs) are rare and their natural history is poorly understood. Available literature indicates aggressive behavior with a significant risk of metastasis.

STUDY DESIGN

Retrospective review of our institutional surgical oncology databases was performed for patients diagnosed with MCATs (2001-2020). We hypothesized that most patients have a low risk of lymph node involvement, recurrence, and death. Kaplan-Meier statistical analysis was used to assess risk of recurrence and 5-year survival.

RESULTS

We identified 41 patients diagnosed with MCATs (median age 59 years, 68% were men). Most patients had long-standing cutaneous lesions (median 24 months) and no palpable adenopathy. Most patients had stage I or II disease (98%). Primary tumors were treated with wide local excision (n = 28 [68%]), Mohs surgery (n = 5 [12%]), or amputation (n = 8 [19%]). Of 25 patients who underwent SLNB (61%), 1 had lymphatic metastasis. These include apocrine carcinoma (1 of 3), digital papillary adenocarcinoma (0 of 8), porocarcinoma (0 of 4), and additional MCAT sub-types (0 of 10). Three patients (7%) had disease recurrence at a median interval of 3.6 years (interquartile range 1.5 to 4.4 years). Five patients (12%) died at a median interval of 7 years (interquartile range 6.7 to 9.2 years), but only 1 patient was known to have succumbed to MCAT. Overall 5-year survival rate was 96% (95% CI, 75% to 99%).

CONCLUSIONS

Despite the historical impression that MCATs have a high metastatic potential, most patients have low recurrence rates and excellent 5-year survival rates. Lymphatic disease identified after SLNB in early-stage tumors is rare and the value of this staging procedure in MCAT remains unclear.

A Rare Case of Porocarcinoma and Trichoblastoma Arising in a Nevus Sebaceus of Jadassohn

Nevus sebaceus of Jadassohn, or "organoid nevus," is a common, benign hamartoma of the skin consisting of epithelial and adnexal components. Its natural history and association with neoplastic growths is well documented. The majority of concomitant neoplasms are benign-trichoblastoma and syringocystadenoma papilliferum are most frequently discovered-but malignant tumors have been described. We present the case of a 58-year-old male with a congenital nevus sebaceus of Jadassohn on his left parietal scalp that had been enlarging, changing color, and bleeding over the prior year. Clinical exam and histology disclosed the presence of a trichoblastoma and porocarcinoma arising within the nevus sebaceus. Porocarcinoma is a rare, intermediately aggressive, malignant eccrine gland tumor that is frequently metastasized at presentation. Otolaryngology performed wide local resection with sentinel lymph node biopsy. This case highlights the diversity of tumors associated with nevus sebaceus of Jadassohn, potential for malignant expansion, and necessity for close monitoring and maintaining a low threshold for biopsy in evolving lesions.

Resolution of Metastatic Subungal Eccrine Porocarcinoma Treated with Intralesional Interleukin-2

Eccrine porocarcinoma is a rare aggressive cutaneous malignancy. Complete surgical excision is the standard of care, although there are high rates of local and distant recurrence. We present a unique case of locally recurrent and metastatic subungal porocarcinoma successfully treated with intralesional interleukin-2.

Mangelnde Nachexzision eines dermatohistologisch suspekten Poroms

Von einem niedergelassenen Hautarzt wurde bei einem Patienten eine Hautveränderung im Bereich des Oberschenkels rechts unter dem Verdacht auf einen epidermalen Naevus exzidiert. Dermatohistologisch wurde die Diagnose „ekkrines Porom“ gestellt. Bei gesteigerter Proliferationsaktivität konnte die Dignität jedoch nicht sicher als gutartig bewertet werden und eine komplette Nachexzision wurde dringend empfohlen. Diese erfolgte weder zeitnah noch nach 11 Monaten, als sich der Patient aufgrund einer Urtikaria erneut vorstellte. Weitere 14 Monate später erfolgte eine Konsultation des Patienten bei einem anderen Hautarzt aufgrund einer plattenförmigen Veränderung im erstbehandelten Bereich des Oberschenkels, wo mittels einer Hautbiopsie ein invasives Porokarzinom gesichert wurde. Eine stationäre Nachexzision sowie ein Tumorstaging wurden in einer dermatologischen Universitätsklinik vorgenommen. 6 Jahre später wurde im Bereich der rechten Leiste eine Lymphknotenmetastase des Porokarzinoms nachgewiesen, die in einer chirurgischen Klinik mittels Lymphknotendissektion sowie adjuvanter Strahlentherapie therapiert wurde.

Von der Schlichtungsstelle wurde zwar ein Diagnosefehler verneint, aber eine schuldhafte Unterlassung der Sicherungsaufklärung und der Veranlassung der Folgebehandlung bejaht. Die Unterlassung einer In toto-Entfernung des ekkrinen Poroms mit dadurch erfolgter Zeitverzögerung des malignen Hauttumors war als fehlerhafte massive Fachstandardunterschreitung einzuordnen; bei korrektem Vorgehen wäre nach ärztlicher Erfahrung eine wesentliche Veränderung des Krankheitsverlaufes zu erwarten gewesen.

Der dermatohistologische Befund von auf Malignität verdächtigen, unvollständig exzidierten Hauttumoren sollte dem Patienten unverzüglich mitgeteilt, eine Nachexzision, sofern indiziert, eindringlich empfohlen und diese Sicherungsaufklärung in der Patientenakte vermerkt werden. Das Versäumnis dieser Pflicht zur Aufklärung und nachfolgenden Behandlung kann einen groben Behandlungsfehler darstellen, der zur Beweislastumkehr für die Kausalität nachfolgend auftretender Gesundheitsschäden des Patienten führt.

A Case Report of Malignant Eccrine Porocarcinoma Involving the Palm Requiring Surgical Excision and Free Flap Reconstruction

Patient: Male, 63-year-old

Final Diagnosis: Eccrine porocarcinoma

Symptoms: Pain

Medication: —

Clinical Procedure: Resection of hand cancer

Specialty: Surgery

Eccrine Porocarcinoma: Avoiding Diagnostic Delay

Skin cancer is the most common cancer within the United States. Reports estimate that 1 in 5 Americans will develop some form of skin cancer. Eccrine porocarcinoma is a rare type of skin cancer of sweat gland origin. Eccrine porocarcinoma is most commonly found on the lower extremities. Clinically it may appear similar to benign skin lesions and it has significant metastatic potential. The authors present a case report with 22 months' follow-up. It describes a multiyear delay in diagnosis involving 3 specialties, including primary care, dermatology, and wound physical therapy. Information is given on techniques when high-risk cutaneous cancers are suspected or encountered. A multispecialty treatment plan is discussed.Levels of Evidence: Level V.

A case of YAP1 and NUTM1 rearranged porocarcinoma with corresponding immunohistochemical expression: Review of recent advances in poroma and porocarcinoma pathogenesis with potential diagnostic utility

Porocarcinoma is a rare malignant adnexal tumor with predilection for the lower extremities and the head and neck region of older adults. This entity may arise de novo or in association with a benign poroma. Porocarcinoma's non-specific clinical appearance, immunohistochemical profile, and divergent differentiation may occasionally be diagnostically challenging. Recently, highly recurrent YAP1 and NUTM1 gene rearrangements have been described in cases of poroma and porocarcinoma. In this report, we present a case of porocarcinoma with squamous differentiation in an 81-year-old woman which harbored rearrangement of the YAP1 and NUTM1 loci and was diffusely immunoreactive for NUTM1. We discuss the recent advancements in the pathogenesis of poromas and porocarcinomas with emphasis on the clinical utility of the NUTM1 antibody.