Eccrine porocarcinoma (malignant eccrine poroma): a clinicopathologic study of 69 cases

Porocarcinoma: a rare cause of lateral cervical tumor

Porocarcinoma is a rare tumor of the eccrine sweat glands that usually disseminates to the regional lymph nodes, but it can also develop distant metastasis. Case presentation: We report the case of a 67 year-old female patient who underwent wide surgical resection of a left cervical cutaneous tumor in a primary care center, for which the histology exam of the specimen was mixed basal cell and squamous cell carcinoma. She was referred to our hospital's oncology clinic and histologic re-evaluation changed the diagnosis to eccrine porocarcinoma (EPC). Computer-tomography (CT) revealed cervical lymphadenopathies for which the patient underwent 4 cycles of chemotherapy, without regression. She subsequently underwent a left upper anterior jugular lymphadenectomy (group IIa) with all nodes being negative and, three months later, she developed a unique adenopathy under the parotid gland that was excised and confirmed to be metastatic. Postoperative external radiotherapy was administered with a good outcome on CT scan. Nine months after her last surgery, the patient did not show any sign of recurrence or distant metastasis. Conclusion: EPC is a challenge, both diagnostically and therapeutically. In the absence of consensus regarding the indications and extent of lymphadenectomy and adjuvant therapy, patients with EPC should be referred to an experienced multidisciplinary team in a tertiary center.

Comparison of Immunohistochemical Expression of Cytokeratin 19, c-KIT, BerEP4, GATA3, and NUTM1 Between Porocarcinoma and Squamous Cell Carcinoma

ABSTRACT

Distinguishing porocarcinoma from squamous cell carcinoma (SCC) is clinically significant; however, differential diagnosis can often be challenging. This study sought to confirm the diagnostic utility of cytokeratin 19, c-KIT, BerEP4, GATA3, and NUTM1 immunohistochemistry in distinguishing porocarcinoma from SCC. Immunohistochemical analysis of cytokeratin 19, c-KIT, BerEP4, GATA3, and NUTM1 in 14 porocarcinomas and 22 SCCs was performed; the extents and intensities of expression of these markers were recorded. The statistical associations of the immunoexpression between porocarcinoma and SCC were analyzed using the Pearson χ2 test. Cytokeratin 19 was positive in 13 (92.9%) of 14 porocarcinomas, and for all the positive cases, staining was strong and evident in >20% of the tumor cells. By contrast, 9 (40.9%) of 22 SCCs expressed cytokeratin 19 (P = 0.0018), of which 6 showed extremely focal (≤10% of the tumor cells) expression. Of the 14 porocarcinomas, 11 (78.6%) cases showed c-KIT positivity, whereas only 3 of 22 SCCs (13.6%) expressed c-KIT focally (P = 0.0001). In addition, BerEP4 immunostaining differed between porocarcinomas and SCCs (57.1% vs. 9.1%, respectively; P = 0.0017). However, no significant difference between the groups was reported in terms of GATA3 expression (57.1% vs. 72.7%, respectively; P = 0.3336). NUTM1 was expressed in 4/14 (28.6%) porocarcinomas but not in the SCCs. Immunohistochemistry for cytokeratin 19, c-KIT, and BerEP4 could be helpful in distinguishing porocarcinomas from SCCs. In addition, NUTM1 immunoexpression is highly specific, although not sensitive, to porocarcinomas. GATA3 immunohistochemistry has no meaningful implications in the differential diagnosis of porocarcinoma and SCC.

Eccrine porocarcinoma: case report and review of the literature

Eccrine porocarcinoma is a rare skin cancer that originates from the acrosyringium of eccrine sweat glands. From the clinical point of view the differential diagnosis with other skin cancers such as basal cell carcinoma and squamous cell carcinoma it is often impossible, only the histopathologic features can lead to the definitive diagnosis. Eccrine porocarcinoma can arise from a previous poroma or de novo, it may recur after surgical excision and cause lymph node and visceral metastasis. There are no international guidelines for treatment or follow-up of patients. The aim of this work was to present a rare case of eccrine porocarcinoma of the scalp successfully treated in our clinic and to extrapolate from the international literature the main clinical and histopathological features of eccrine porocarcinoma and the various experiences regarding the types of treatment.

A systematic review of periungual eccrine neoplasms

Eccrine tumors are a rare cutaneous adnexal neoplasm originating from the sweat glands. The periungual region represents an uncommon localization for these neoplasms. We analyzed all published demographic, clinical, and treatment data on periungual eccrine tumors. A systematic review following PRISMA guidelines was performed of articles published prior to March 2021. Articles were included in the review if a full-text English version was available. Of the surveyed literature, 27 full-text case reports were included in the final analysis. Benign eccrine poroma and porocarcinoma were the most common tumor subtypes (nine and eight cases, respectively). Males were only affected by poroma and porocarcinoma, while females were affected by all tumor subtypes. The first toe was the most common lower extremity affected. Misdiagnosis led to delayed treatment in 25% of cases. As such, while periungual eccrine neoplasms are rare diagnoses, the nonspecific presentations of these growths raise concerns about misdiagnosis and delayed treatment. Further research is needed related to sex-differences in the epidemiology of these growths and into the prevalence of the first toe as a location. These tumors should be considered in the differential diagnosis for nail unit afflictions.

Rare case of large eccrine poroma of the eyelid

Eccrine poroma is a rare tumor arising from sweat glands with common location being soles and palms. We are reporting a case of 70-year male patient with large lower lid mass lesion. Owing to its location and history of growth, malignancy was suspected. Biopsy proved it to be eccrine poroma which is a benign lesion. Complete excision with lid reconstruction was done. Eccrine poroma, though rare, should be kept in the differential diagnosis of eyelid tumors. Owing to the risk of malignant transformation and difficulty in clinical differentiation between poroma and porocarcinoma, wide excision should be done.

Management of brain metastasis from eccrine porocarcinoma: illustrative case

BACKGROUND

Eccrine porocarcinoma (EP) is a rare malignant skin neoplasm, and there are still many unknowns regarding its natural history and treatment. Due to its scarcity, associated brain metastasis is a far rarer condition.

OBSERVATIONS

A 71-year-old-woman with a history of EP was diagnosed with brain metastasis. In her clinical course, the patient underwent tumor removal surgery twice and Gamma Knife radiosurgery (GKRS) four times. The tumor showed a good response to radiotherapy. The histopathological findings of the brain tumor were consistent with those of the primary skin tumor.

LESSONS

There are only a few case reports referring to the detailed treatment, especially with GKRS, of brain metastasis from EP. Few reports have presented a detailed histopathological comparison between the primary skin lesion and the metastatic brain lesion. Herein, the authors have described the clinical course, histological features, and results of multidisciplinary treatment for brain metastasis of EP.

[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.

A Case of Eccrine Poromatosis in a Patient with a History of Chemotherapy Due to Stomach Cancer

An eccrine poroma (EP) is a benign adnexal tumor that typically presents as a single lesion. Eccrine poromatosis defined as multiple EPs is an uncommon presentation. A 54-year-old male had undergone operation for stomach cancer 10 years prior and insisted that he had also taken adjuvant chemotherapy. The patient presented with six reddish papules and nodules scattered on the trunk and extremities for 3 years. The histopathologic findings from all six lesions were consistent with EP. No local recurrence was observed after complete removal through punch biopsies. We report a rare case of eccrine poromatosis in the patient with gastric cancer, suspected of being caused by chemotherapy.

Sebaceous carcinoma arising from sebaceoma

Sebaceous neoplasms are rare adnexal tumors that can present a challenge to clinicians. Only four cases of sebaceous carcinoma with sebaceoma have been reported in the literature. Herein, we describe the case of a sebaceous carcinoma originating from a sebaceoma in a solitary nodule of the posterior neck. Immunohistochemically, the tumor cells were strongly positive for epithelial membrane antigen and p53. It is possible that adnexal carcinomas may arise from malignant transformation of their benign counterparts as well as de novo. Malignant transformation was likely in this case because the lesion was composed of distinct benign and malignant components, and the benign component showed the typical histopathological features of sebaceoma. This case underscores the fact that partial and superficial biopsies sometimes may not provide the correct diagnosis. If a surgeon suspects malignancy based on a clinical examination, then it is mandatory to perform a deep biopsy.

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.

Poroid adnexal skin tumors with YAP1 fusions exhibit similar histopathologic features: A series of six YAP1-rearranged adnexal skin tumors

BACKGROUND

Adnexal skin tumors are diagnostically challenging with few known molecular signatures. Recently, however, YAP1-MAML2 and YAP1-NUTM1 fusions were identified in poroid adnexal skin tumors.

METHODS

Herein, we subjected eight poroid adnexal skin tumors (three poromas and five porocarcinomas) to fusion gene analysis by whole transcriptome sequencing and next-generation DNA sequencing analysis.

RESULTS

YAP1 fusions were identified in six cases. YAP1-NUTM1 fusions were identified in two poromas and three porocarcinomas. A single case of porocarcinoma harbored a YAP1-MAML2 fusion. Two cases were negative for gene fusion. All cases that harbored YAP1-NUTM1 fusions showed nuclear protein in testis (NUT) expression by immunohistochemistry, with NUT being negative in the YAP1-MAML2-positive case. In this case series, we provide a detailed histopathologic description of six YAP1-fused poroid skin tumors, which we show harbor reproducible histopathologic features, to include broad, bulbous tumor tongues with admixtures of basaloid, poroid cells punctuated by squamatized cuticles and ductules, with uniform tumor nuclei featuring frequent grooves and pseudonuclear inclusions.

CONCLUSIONS

Awareness of the characteristic histopathologic features of YAP1-fused poroid adnexal skin tumor is a step toward a more reproducible classification of adnexal skin tumors as well as a step toward targeted therapy for metastatic and/or unresectable examples of this poroid group of neoplasms.

Eccrine Porocarcinoma: A Rare Tumor of the Eyelid With a Novel Histopathological Finding of Free Tumor Cells in the Tear Film

The authors present a case of an eyelid eccrine porocarcinoma, a very rare malignant sweat gland tumor characterized histopathologically by nests of atypical poromatous cells and the presence of duct-like lumina. Histopathologic analysis of this case also exhibited numerous loose tumor cells in the adjacent tear film, a finding that has not been previously described.

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.

NUT Is a Specific Immunohistochemical Marker for the Diagnosis of YAP1-NUTM1-rearranged Cutaneous Poroid Neoplasms

YAP1-NUTM1 fusion transcripts have been recently reported in poroma and porocarcinoma. NUTM1 translocation can be screened by nuclear protein in testis (NUT) immunohistochemistry in various malignancies, but its diagnostic performance has not been thoroughly validated on a large cohort of cutaneous epithelial neoplasms. We have evaluated NUT immunohistochemical expression in a large cohort encompassing 835 cases of various cutaneous epidermal or adnexal epithelial neoplasms. NUT expression was specific to eccrine poromas and porocarcinoma, with 32% of cases showing NUT expression. All other cutaneous tumors tested lacked NUT expression, including mimickers such as seborrheic keratosis, Bowen disease, basal cell carcinoma, squamous cell carcinoma, Merkel cell carcinoma, nodular hidradenoma, and all other adnexal tumors tested. Remarkably, NUT expression was more frequent in a distinct morphologic subgroup. Indeed, 93% of poroid hidradenoma (dermal/subcutaneous nodular poroma, 13/14) and 80% of poroid hidradenocarcinoma cases (malignant poroid hidradenoma, 4/5) showed NUT expression, in contrast to 17% and 11% of classic poroma (4/23) and porocarcinoma cases (4/35), respectively. RNA sequencing of 12 NUT-positive neoplasms further confirmed the presence of a YAP1-NUTM1 fusion transcript in all cases, and also an EMC7-NUTM1 gene fusion in a single case. In the setting of a cutaneous adnexal neoplasm, nuclear expression of NUT accurately and specifically diagnosed a specific subgroup of benign and malignant poroid tumors, all associated with a NUTM1 fusion, which frequently harbored a poroid hidradenoma morphology.

Utility of YAP1 and NUT immunohistochemistry in the diagnosis of porocarcinoma

BACKGROUND

Porocarcinoma is the malignant counterpart of poroma, a benign tumor derived from the eccrine or apocrine units. In contrast to poroma, porocarcinoma is rare and its diagnosis may be challenging. Recent work has identified YAP1-associated gene fusions in most poromas, and a subset of porocarcinomas. These included YAP1-MAML2 and YAP1-NUTM1, the latter being enriched in porocarcinomas over poromas.

METHODS

We studied YAP1 C-terminus and NUT immunohistochemistry in a cohort of 12 porocarcinomas, 10 poromas, 10 squamous cell carcinomas, and 6 hidradenocarcinomas.

RESULTS

Seven of 12 (58%) porocarcinomas showed loss of YAP1 C-terminus expression, consistent with a YAP1 fusion. Of these seven, five showed NUT positivity, implying the presence of the YAP1-NUTM1 fusion. One of 12 (8%) cases showed NUT positivity, but retention of YAP1 C-terminus expression, consistent with a non-YAP1 NUT-associated fusion. Eight of 10 (80%) poromas showed loss of YAP1 C-terminus expression and negative NUT staining, consistent with non-NUT YAP1 fusions. All squamous cell carcinomas and hidradenocarcinomas retained YAP1 C-terminus expression and were negative for NUT.

CONCLUSION

YAP1 C-terminus and NUT immunohistochemistry may be helpful in the diagnosis of porocarcinoma, with the combination of YAP1 C-terminus loss and NUT positivity being particularly informative.

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

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.

Engrailed Homeobox 1 and Cytokeratin 19 Are Independent Diagnostic Markers of Eccrine Porocarcinoma and Distinguish It From Squamous Cell Carcinoma

OBJECTIVES

The diagnostic utility of En1 in the histopathologic differentiation of eccrine porocarcinoma (EPC) from invasive squamous cell carcinoma (SCC) was investigated.

METHODS

Expression of En1 and CK19 in 16 cases of EPC was immunohistochemically examined and compared with that in 32 cases of SCC.

RESULTS

In all 16 EPCs, En1 was expressed in 3% to 100% of tumor cells. In 20 of the 32 SCCs, En1 was expressed in 3% to 90% of tumor cells. A total of 13 of the 16 EPCs and five of the 32 SCCs were judged as En1 positive, with a cutoff value of 25%. In addition, 11 of the 16 EPCs and four of the 32 SCCs were CK19 positive. The frequencies of En1- and CK19-positive cases were significantly higher in EPCs than in SCCs. In a logistic regression analysis for predicting EPC, En1 and CK19 were independent markers. When expression patterns of En1 and CK19 were combined, none of the 32 SCCs was both positive. In contrast, 15 of the 16 EPCs were positive for either En1 or CK19.

CONCLUSIONS

A combination of En1 and CK19 expression can improve the accuracy of histologic diagnosis of EPC.

Intergluteal Cleft Eccrine Porocarcinoma with Metastasis to Inguinal Region and Lung: Case Report and Review of the Literature

Eccrine porocarcinoma (EPC) is an infrequent cutaneous neoplasm, and was described in 1963 by Pinkus and Mehregan. It is a rare type of skin tumor (0.005-0.01% of all skin tumors). Less than 300 cases have been described in the entire world medical literature. To our knowledge, no case of intergluteal cleft EPC has been reported in the literature in English and Spanish to date, so this would be the first reported case of such pathology. Metastatic EPC is less frequent, since only <10% of metastatic type have been reported and the rest as localized disease. The primary treatment of choice is surgical wide local excision of the tumor with histological confirmation of tumor-free margins. Prognosis is difficult to determine because of the rarity of EPC and the variations in natural history. There are no data to support the use of adjuvant chemotherapy or radiotherapy, and there are currently no agreed criteria to define patients at high risk of relapse. We present a 67-year-old man with intergluteal cleft eccrine tumor by biopsy. Metastasis to left inguinal region and lung was reported by contrasted abdominal and chest computed tomography. He started chemotherapy based on etoposide, vincristine, carboplatin. A review of pertinent literature is provided.

Occurrence of metastatic eccrine porocarcinoma in an immunosuppressed patient

Background

Eccrine porocarcinoma is a rare malignancy accounting for 0.005 to 0.01% of all cutaneous tumors. However, its etiology is not well established. Herein we are reporting the occurrence of metastatic porocarcinoma of the back in a patient with a history of multiple cutaneous malignancies and chronic immunosuppression.

Case presentation

A 79-year-old male with a history of long-term immunosuppressive therapy for left lung transplantation and multiple cutaneous malignancies including melanoma, presented with an enlargening plaque on the right upper back. Biopsy demonstrated an infiltrative epithelial tumor with aggressive histology and ductal formation. Immunohistochemical stains for p63, CK-5/6, and CEA were diffusely positive, while CK-7 and CK-20 were negative. A diagnosis of eccrine porocarcinoma was made. He underwent complete wide excision with negative margins of the right upper back in January 2018. In November 2018, he was found to have a right posterior shoulder mass, positive right axillary lymph nodes, superficial right upper back soft tissue masses and lymphangitic carcinomatosis involving the left lung. He was transitioned to comfort care and subsequently passed from metastatic disease in December 2018.

Conclusion

The occurrence of eccrine porocarcinoma in a patient on long term immunosuppressive therapy for lung transplantation suggests a possible role for chronic immunosuppression in the induction of a subset of eccrine porocarcinomas, as in other cutaneous malignancies.

Multiple Plantar Poromas in a Stem Cell Transplant Patient

Poromatosis, or the formation of multiple eccrine poromas, is associated with chronic immunosuppression, lymphoproliferative neoplasms, and stem cell transplantation, though the etiology and clinical significance remain poorly understood. Eccrine poromas are asymptomatic, may appear years after treatment, and overlap morphologically with other diagnoses, particularly human papillomavirus-associated verrucae, to which immunosuppressed patients may be predisposed and commonly occur in similar sites. We report a 47-year-old female on chronic immunosuppression who developed multiple plantar eccrine poromas three years after achieving acute myeloid leukemia (AML) remission following treatment with chemotherapy, total body irradiation, and allogenic stem cell transplantation. We propose that early recognition, timely treatment, and regular follow-up skin examinations are necessary in the setting of multiple poromas to reduce the risk of malignancy and avoid delays in diagnosis.

YAP1-MAML2-Rearranged Poroid Squamous Cell Carcinoma (Squamoid Porocarcinoma) Presenting as a Primary Parotid Gland Tumor

Porocarcinoma (synonym: malignant eccrine poroma) is a rare aggressive carcinoma type with terminal sweat gland duct differentiation. The squamous variant of porocarcinoma is even less frequent and might be indistinguishable from conventional squamous cell carcinoma (SCC). We herein describe the first case of a carcinoma presenting as a primary parotid gland malignancy in a 24-year-old male without any other primary tumor. Total parotidectomy and neck dissection were performed followed by adjuvant chemoradiation. The patient remained alive and well 10 months after diagnosis. Histology showed keratinizing SCC infiltrating extensively the parotid gland with subtle poroid cell features. Oncogenic HPV infection was excluded by DNA-based testing. NGS analysis using the TruSight RNA fusion panel (Illumina) revealed a novel YAP1-MAML2 gene fusion. This gene fusion was reported recently in a subset of cutaneous porocarcinoma and poroma. This case of poroid SCC (or squamoid porocarcinoma) adds to the differential diagnosis of SCC presenting as parotid gland tumor and highlights the value of molecular testing in cases with unusual presentation.

Eccrine Porocarcinoma: A Multicenter Retrospective Study with Review of the Literatures Reported in Korea

BACKGROUND

Eccrine porocarcinoma (EPC) is a rare malignant cutaneous adnexal tumor. Other than several scattered case reports, no comprehensive review on EPC has been conducted in Korea.

OBJECTIVE

To clinicopathologically review all EPC cases from our institutions as well as those reported in Korea.

METHODS

Medical records and histopathological slides of EPC cases in the skin biopsy registries of our institutions were retrospectively reviewed. Additionally, EPC cases reported in Korea before June 2019 were retrieved by searching the PubMed, KoMCI, KoreaMed, and KMbase databases.

RESULTS

Nine EPC cases from our institutions were included in the study. In addition, 27 reports of 28 patients with EPC were reported in Korea. A total of 37 patients with EPC were identified, consisting of 19 males (male:female ratio, 1.06:1; mean age at diagnosis, 65.6 years). The most common site of primary tumor was the head and neck (29.7%). Wide excision was the most common (78.4%) treatment method. Initial metastasis work-up imaging studies were performed in 18 patients (48.6%), and metastasis was confirmed in eight patients (21.6%).

CONCLUSION

EPC is a rare cutaneous carcinoma in Korea. EPC usually affects elderly patients, with no sexual predilection. Due to possible metastasis, careful diagnosis and appropriate metastasis work-ups are warranted in EPC.

YAP1-NUTM1 Gene Fusion in Porocarcinoma of the External Auditory Canal

Gene fusions involving the NUTM1 gene (NUT) represent defining genetic markers of a highly aggressive carcinoma type with predilection for the midline structures of children and young adults, hence the original description as NUT midline carcinoma. Recent studies have increasingly documented involvement of the NUTM1 gene in the pathogenesis of other entities as well. We herein describe two cases of auditory canal carcinomas with features of porocarcinoma, both harboring a newly described YAP1-NUTM1 gene fusion. Patients were males aged 28 and 82 years who presented with slowly growing lesions in the external auditory canal. Histologic examination showed monomorphic basaloid and squamoid cells arranged into organoid solid aggregates, nests, ducts, small cysts, and focal pseudocribriform pattern with variable mitotic activity, infiltrative growth, and focal squamous differentiation, particularly in the most superficial part of the tumor. Immunohistochemistry revealed consistent reactivity for CK5, p63 and SOX10 and diffuse aberrant expression of TP53. CK7 expression was limited to a few luminal ductal cells. The androgen receptor and S100 were negative. Next generation sequencing (TruSight RNA fusion panel, Illumina) revealed the same YAP1-NUTM1 gene fusion in both tumors, which was subsequently confirmed by NUT-FISH and the monoclonal anti-NUT antibody. These cases represent a novel contribution to the spectrum of NUT-rearranged head and neck malignancies. This adnexal carcinoma variant should not be confused with the highly lethal NUT carcinoma based on NUT immunoreactivity alone.

Eccrine Porocarcinoma with Squamous Differentiation in a Patient with Oculocutaneous Albinism

Eccrine porocarcinoma is a rare malignant skin appendage tumor of sweat gland origin. Eccrine porocarcinoma arising in a patient of oculocutaneous albinism is extremely rare and only two cases have been reported in English literature to the best of our knowledge. Out of the two cases of eccrine porocarcinoma in oculocutaneous albinism, one case had squamous differentiation. We report a case of eccrine porocarcinoma with squamous differentiation in a 39-year-old male, who presented with a nodular lesion on the upper left chest wall. He also had nodal and distant cutaneous metastasis.

Eccrine porocarcinoma of the head and neck: Meta-analysis of 120 cases

BACKGROUND

The aim of the study is to analyze potential prognostic factors and to evaluate therapy strategies regarding clinical outcome in patients with eccrine porocarcinoma (EPC) of the head and neck.

METHODS

One hundred and sixteen EPC cases from ninety studies and four authors' EPC cases were included in the meta-analysis.

RESULTS

At an average follow up of 20.48 months, the 3-year overall survival and regional recurrence rate were 70.3% and 19.0%, respectively. Patients without surgical treatment had a significantly worse 3-year overall survival. Mohs microscopic surgery led to significantly less occurrence of regional recurrences compared to wide excision. An ulcerating lesion, high mitotic activity, and lymphovascular invasion were significant prognostic factors.

CONCLUSION

Surgical resection is the cornerstone in the therapy of EPC and represents the therapeutic modality that offers the best chance of disease-free survival. Due to the high probability of recurrence, close follow-ups are strongly recommended.

Emerging entities in NUTM1-rearranged neoplasms

Structural alterations of NUTM1 were originally thought to be restricted to poorly differentiated carcinomas with variable squamous differentiation originating in the midline organs of children and adolescents. Termed NUT carcinomas (NCs), they were defined by a t(15;19) chromosomal rearrangement that was found to result in a BRD4-NUTM1 gene fusion. However, the use of DNA and RNA-based next-generation sequencing has recently revealed a multitude of new NUTM1 fusion partners in a diverse array of neoplasms including sarcoma-like tumors, poromas, and acute lymphoblastic leukemias (ALLs) that we propose to call NUTM1-rearranged neoplasms (NRNs). Intriguingly, the nosology of NRNs often correlates with the functional classification of the fusion partner, suggesting different oncogenic mechanisms within each NRN division. Indeed, whereas NCs are characterized by their aggressiveness and intransigence to standard therapeutic measures, the more positive clinical outcomes seen in some sarcoma and ALL NRNs may reflect these mechanistic differences. Here we provide a broad overview of the molecular, nosological, and clinical features in these newly discovered neoplastic entities. We describe how aberrant expression of NUTM1 due to fusion with an N-terminal DNA/chromatin-binding protein can generate a potentially powerful chromatin modifier that can give rise to oncogenic transformation in numerous cellular contexts. We also conclude that classification, clinical behavior, and therapeutic options may be best defined by the NUTM1 fusion partner rather than by tumor morphology or immunohistochemical profile.

Eccrine Porocarcinoma: A Case Report of a Rare and Aggressive Cutaneous Tumour

Eccrine porocarcinoma (EPC) is an extremely rare, adnexal carcinoma that represents less than 0.01% of all cutaneous malignancies. An aggressive tumour with a high recurrence rate, it has a tendency to metastasise to regional lymph nodes. Once metastasis has occurred, mortality rate increases to 75%-80% and thus survival is dependent on adequate and timely resection of the lesion. EPCs are frequently missed as a differential diagnosis due to their rarity and non-specific appearance, which can lead to serious consequences for patients. Consequently, EPCs are an important diagnosis for clinicians to be aware of and consider when evaluating cutaneous lesions. 

We present a case of EPC of the knee, which was initially misdiagnosed as a benign lesion on magnetic resonance imaging (MRI). We discuss the use of MRI in aiding assessment of EPCs.

Zosteriform Lymphangitic Metastases of Eccrine Porocarcinoma

Eccrine porocarcinoma (EPC) is a rare malignant neoplasm which originates from the intraepidermal portion of eccrine sweat glands or acrosyringium. Here, we report a unique case of cutaneous metastases of EPC presenting with an erosive plaque on the left thumb and multiple nodules on left forearm. The histopathological examination of the wrist lesion revealed islands of basaloid tumor cells with eosinophilic cytoplasm, downward infiltrating growths, ductal differentiation, and intracytoplasmic lumen formations and focally connected to the epidermis. Acrosyringeal differentiation was confirmed by positive immunohistochemical staining using antibodies to carcinoembryonic antigen (CEA) and epithelial membrane antigen (EMA) in some of porocarcinoma cells. Lymphatic embolization was shown by immunostaining of podoplanin. To the best of our knowledge, this is the first reported EPC case with a primary lesion on the left thumb and zosteriform growth pattern of lymphangitic metastases on left forearm. Our case highlights the diagnostic challenges and reveals lymphangitic metastasis mode of EPC.

Metastatic porocarcinoma achieving complete radiological and clinical response with pembrolizumab

A 67-year-old woman presented in 2012 with a crusty nodule on the left lower limb. Histopathological examination at this time reported a poorly differentiated squamous cell carcinoma (SCC). Two years later, she underwent lymphadenectomy and radiotherapy due to unilateral inguinal and pelvic sidewall nodal metastases. The following year she required excision of two subcutaneous lesions, reported pathologically to be SCC metastases. Further imaging following cyberknife radiotherapy to new brain metastases demonstrated widespread metastatic visceral disease. Twelve cycles of carboplatin and capecitabine failed to halt disease progression. In February 2017, she commenced pembrolizumab, achieving an excellent response and currently has no clinical or radiological evidence of disease. Given the unusual behaviour of her cancer, a histopathological review was requested. The diagnosis was revised to that of porocarcinoma (PC). This represents the first documented case of PC treated with immunotherapy. As of March 2019, the patient remains free of disease.

An Overview of Uncommon Cutaneous Malignancies, Including Skin Appendageal (Adnexal) Tumours and Sarcomas

A standardised classification of malignant skin appendageal (adnexal) tumours and sarcomas is required for improved patient management and prognosis. This has been hindered by considerable morphological variation both within and between tumour types, the use of many synonyms for the same tumour types and variation in classification between pathologists. This update uses the improved classification in the 2018 WHO classification of skin tumours as the basis to discuss malignant skin appendageal tumours, sarcomas and cutaneous metastases that regularly present to skin cancer clinicians, multidisciplinary skin cancer teams and tumour boards, with current evidence for management, where appropriate.

Primary eccrine porocarcinoma of the thumb with multiple metastases: a case report and review of the literature

We present a case of primary eccrine porocarcinoma of the thumb in a 56-year-old male who ultimately developed multiple metastases. With so few cases of such lesions and their aggressive nature, accurate diagnosis and prompt surgical management is essential.

Eccrine Porocarcinoma on the Lateral Nose Wall: A Rare Case Report

Eccrine porocarcinoma (EPC) is an uncommon malignant tumor derived from the eccrine sweat glands. We present a case of EPC on the lateral nose wall, in which the tumor was excised, and the resultant defect was reconstructed using a nasolabial flap. A 66-year-old female was referred to the Department of Plastic and Reconstructive Surgery to receive treatment for a cutaneous tumor on her right lateral nose wall, which had been growing rapidly for 3 months. Histological analysis of a biopsy specimen of the tumor suggested that it was a squamous cell carcinoma. Surgical excision was performed with a 3-mm margin. The tumor was histologically diagnosed as an EPC. EPC exhibits various pathological features; therefore, it is often confused with other malignant cutaneous tumors. We consider that histologically examining surgical specimens obtained via total resection, rather than incisional biopsy specimens, is important for correctly diagnosing EPC.

Malignant Chondroid Syringoma: A Report of Two Cases with a Sarcomatous Mesenchymal Component

Malignant chondroid syringoma (MCS; malignant mixed tumour) is a rare neoplasm typically arising on the extremities and trunk. We are report 2 unique cases of MCS, one occurring on the scalp of a 78-year-old man and the other on the trunk of a 72-year-old woman. Both tumours harboured malignant epithelial and malignant mesenchymal components. The latter was represented by liposarcoma in the first case. The malignant components of the second tumour comprised spindle cell squamous cell carcinoma (SCC) and osteosarcoma. Origin from a pre-existing benign chondroid syringoma was clearly evident in both neoplasms. The presence of heterologous malignant mesenchymal components, however, is hitherto unreported in the context of MCS, while a spindle cell SCC component is exceptionally rare. The 2 cases presented herein highlight an expanded morphological spectrum of MCS, with resultant blurring of the boundaries between MCS and cutaneous carcinosarcoma.

A Painful Step - Pendulating Plantar Eccrine Poroma

BACKGROUND

Eccrine poroma is a benign tumour of eccrine duct epithelium. The usual clinical presentation is nodular.

CASE REPORT

We present a 78-year-old man with a painful pendulating flesh-coloured malodorous plantar tumour. Differential diagnoses included telangiectatic granuloma, acrochordon, basal cell or squamous cell carcinoma, cylindroma, amelanotic melanoma, and verruca. Microbiological investigations identified numerous bacteria including Corynebacterium striatum, Streptococcus dysgalactiae, Staphylococcus aureus, Citrobacter koseri. We performed surgery since the tumour hampered his mobility. Histopathology revealed a well-circumscribed tumour composed of cuboidal cells with eosinophilic cytoplasm. Healing was unremarkable.

CONCLUSIONS

Pendulating plantar eccrine poroma is a rare clinical presentation of this benign adnexal tumour. Often asymptomatic, in some cases the tumour may become painful. Because of the bacterial colonisation, it could lead to deep soft tissue infections. Malignant transformation is possible. Surgical removal is the treatment of choice.

Recurrent YAP1-MAML2 and YAP1-NUTM1 fusions in poroma and porocarcinoma

Poroma is a benign skin tumor exhibiting terminal sweat gland duct differentiation. The present study aimed to explore the potential role of gene fusions in the tumorigenesis of poromas. RNA sequencing and reverse transcription PCR identified highly recurrent YAP1-MAML2 and YAP1-NUTM1 fusions in poromas (92/104 lesions, 88.5%) and their rare malignant counterpart, porocarcinomas (7/11 lesions, 63.6%). A WWTR1-NUTM1 fusion was identified in a single lesion of poroma. Fluorescent in-situ hybridization confirmed genomic rearrangements involving these genetic loci. Immunohistochemical staining could readily identify the YAP1 fusion products as nuclear expression of the N-terminal portion of YAP1 with a lack of the C-terminal portion. YAP1 and WWTR1, also known as YAP and TAZ, respectively, encode paralogous transcriptional activators of TEAD, which are negatively regulated by the Hippo signaling pathway. The YAP1 and WWTR1 fusions strongly transactivated a TEAD reporter and promoted anchorage-independent growth, confirming their tumorigenic roles. Our results demonstrate the frequent presence of transforming YAP1 fusions in poromas and porocarcinomas and suggest YAP1/TEAD-dependent transcription as a candidate therapeutic target against porocarcinoma.