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The genetic landscape of rare benign tumours and their malignant counterparts is still largely unexplored. While recent work showed that mutant HRAS is present in subsets of poromas and porocarcinomas, a more comprehensive genetic view on these rare adnexal neoplasms is lacking. Using high-coverage next generation sequencing, we investigated the mutational profile of 50 cancer-related genes in 12 cases (six poromas and six porocarcinomas). Non-synonymous mutations were found in two-thirds of both poromas and porocarcinomas. Hotspot HRAS mutations were identified in two poromas (p.G13R and p.Q61R) and one porocarcinoma (p.G13C). While in poromas only few cases showed single mutated genes, porocarcinomas showed greater genetic heterogeneity with up to six mutated genes per case. Recurrent TP53 mutations were found in all porocarcinomas that harboured mutated genes. Non-recurrent mutations in porocarcinomas were found in several additional tumour suppressors (RB1, APC, CDKN2A, and PTEN), and genes implicated in PI3K-AKT and MAPK signalling pathways (ABL1, PDGFRA, PIK3CA, HRAS, and RET). UV-associated mutations were found in TP53, APC, CDKN2A, PTEN, and RET. In conclusion, our study confirms and extends the spectrum of genetic lesions in poromas and porocarcinomas. While poromas exhibited only few mutations, which did not involve TP53, the majority of porocarcinomas harboured UV-mediated mutations in TP53 with some of these cases showing considerable genetic heterogeneity that may be clinically exploitable., (Copyright © 2017 Royal College of Pathologists of Australasia. Published by Elsevier B.V. All rights reserved.)

Eccrine poroma is a benign neoplasm of the terminal duct. It is commonly located in distal extremities but rarely present in head and neck. This report mainly describes a case of external nose eccrine poroma. We will clarify the disease from pathology; histopathological examination; diagnosis; clinical manifestations to prognosis., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Clinical Otorhinolaryngology Head and Neck Surgery.)

Eccrine poromas and porocarcinomas are adnexal tumors derived from the sweat duct epithelium. However, eccrine poroma is benign in nature, whilst eccrine porocarcinoma is regarded as its malignant counterpart. We report the case of a man who presented simultaneously with an eccrine poroma and eccrine porocarcinoma. Both lesions had no clear distinctive features, enhancing the need of high-level clinical suspicion together with surgical excision and histopathology for prompt diagnosis confirmation.

A 75-year-old man with human immunodeficiency virus infection and numerous biopsy-proven warts for 10 years, refractory to cryosurgery, cimetidine, and topical imiquimod, presented with numerous pink to hypopigmented verrucous papules and plaques involving the face, trunk, buttocks, and groin. Laboratory evaluation revealed a CD4 T-cell count of 62 cells per microliter and human immunodeficiency virus viral load of <117 copies per milliliter. Biopsy of a plaque groin lesion was performed. Histopathology revealed vertically oriented anastomosing strands of basaloid epithelium arising from multiple points along the epidermis in a background fibrovascular stroma. Ductal differentiation was identified. Areas of epidermis showed compact orthokeratosis, coarse hypergranulosis, and keratinocytes with abundant steel-blue-gray cytoplasm, indicative of viral cytopathic changes. Cytologic atypia was not identified. Human papillomavirus (HPV) genotyping of this lesion was positive for types 5 and 14. Overall, the findings were consistent with epidermodysplasia verruciformis in association with eccrine syringofibroadenoma (ESFA). The patient was subsequently treated with acitretin and showed clinical improvement. ESFA is an uncommon benign adnexal tumor with unknown pathogenesis. Although its association with HPV has rarely been reported, ESFA in the setting of acquired epidermodysplasia verruciformis has not been described. The development of ESFA in this case may be the result of HPV-induced cellular transformation.

We examined 384 cases of poroid neoplasms. Most cases (n = 279, 72.7%) exhibited the features of only one subtype. One hundred and ninety-eight cases (51.6%) showed only the features of poroma (P), 20 (5.2%) hidroacanthoma simplex (HS), five (1.3%) dermal duct tumor (D) and 56 (14.6%) hidradenoma (HA). Composite tumors of those four subtypes were observed in 105 cases (27.3%). In the trunk and lower extremities, lesions with the features of P were observed at higher rates than other sites. Those of HS and D were more frequently observed in the lower extremities. Those of HA were seen at higher rates in the scalp, face, neck and genitalia. Ninety-eight cases (25.5%) showed decapitation secretion and diagnosed as apocrine type lesion. Apocrine type lesions were frequently observed in the lesions on the genitalia (40.0%), scalp (31.8%) and trunk (31.1%), whereas at lower rates in those on the neck (21.4%) and lower extremities (24.0%). In apocrine type cases, the lesions were located more frequently on the scalp and trunk than non-apocrine type, whereas were less frequent on extremities. The rate of apocrine type lesions in the cases with only one subtype (19.7%) was lower than that of those with composite tumors (41.0%). In the apocrine type (43.9%), composite tumors are more frequent than in the non-apocrine type (21.7%). In D (40.8%) and HA (32.3%), apocrine type lesions were more frequently observed than other subtypes. In conclusion, it should be noted that a quarter of poroid neoplasms are composite tumors and/or show apocrine differentiation., (© 2016 Japanese Dermatological Association.)

Hidroacanthoma simplex is a rare intraepidermal neoplasia that arises from the acrosyringial portion of the eccrine duct. Malignant transformation of hidroacanthoma simplex is reported in the literature and the treatment is performed with wide excision or Mohs micrographic surgery. We report the first case successfully treated with cryosurgery with a long-term follow up.

Eccrine porocarcinoma (EPC) is a rare malignant skin tumor presumably arising from the intraepidermal ductal portion of the sweat gland. EPC occasionally mimics eccrine poroma (EP), seborrhea keratosis (SK), basal cell carcinoma (BCC), pyogenic granuloma (PG) and amelanotic melanoma with its clinical appearance as a pink nodule. Dermoscopy is an invaluable technique in diagnosing skin tumors. However, few cases of EPC have been reported using dermoscopic images, and their details were not well examined. Here, we present three histopathologically proven cases of EPC and summarize their dermoscopic findings together with five previously reported cases. None of the eight cases showed dermoscopic evidence indicative of SK (comedo-like openings, milia-like cysts, fissures and ridges, and hairpin vessels with white halo), BCC (blue-gray ovoid nests, multiple blue-gray globules, wheel-like structures, shiny white areas, leaf-like areas and arborizing vessels) or PG (reddish homogeneous area with collarette and white rail lines). A milky red area, which was suggestive of amelanotic melanoma, was not detectable in any cases. Seven cases exhibited a polymorphous vascular pattern mainly consisting of hairpin, linear-irregular and dotted vessels. A combination of round-to-oval pink-white structureless areas and white-to-pink halo was observed in five of eight cases, with one case showing the white-to-pink halo alone. Our investigation revealed that the dermoscopic characteristic of EP was also observed in discrete areas of EPC lesions. Thus, it is possible that the histopathological architecture of EPC contains portions of benign EP-like components. Awareness of this dermoscopic aspect of EPC may be helpful when diagnosing pink nodules., (© 2015 Japanese Dermatological Association.)

We herein report a patient who clinically presented with a yellowish, flat plaque that histopathologically showed a benign lesion mainly composed of intraepidermal basaloid nests with sebaceous differentiation. This lesion was considered to be fundamentally apocrine poroma (hidroacanthoma simplex type) with sebaceous differentiation. Nests composed of typical poroid cells were seen, and the results of immunostaining for lumican supported this diagnosis and excluded the possibility of clonal seborrheic keratosis. The sebaceous differentiation in apocrine poromas mostly occurs in Pinkus type lesions, and is usually seen in only part of the lesions, as solitary, mature sebocytes within the poroma nests. However, our apocrine poroma case was unique not only in that sebaceous differentiation occurred in the hidroacanthoma simplex type, but also in that it was observed extensively (approximately 60% of the nests). We therefore called this lesion an 'intraepidermal benign sebaceous neoplasm'. Although it may be hard to differentiate sebaceous germinative cells (seen in sebaceoma) from poroid cells, in this case, some poroma nests could be judged to neighbor or contain the sebaceoma-like areas. Therefore, the presented apocrine poroma was considered to have some features of (intraepidermal and dermal) sebaceoma., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Apocrine poromas are rare and distinctive benign adnexal neoplasms featuring tumor cells differentiating toward folliculosebaceous-apocrine units. We report an extremely rare case with multiple apocrine poromas in a single patient. Fifteen tumors were distributed on the head, neck, forearm and axilla of a 74-year-old man. All tumors were mostly composed of poroid cells that surrounded variably sized duct spaces, some of which exhibited decapitation secretion. The poroid cells were continuous with infundibulum-like structures that contained aggregates of mature sebocytes. The patient had no family history of similar tumors and no history of immunosuppressive therapy. This is the first report of multiple apocrine poromas, suggesting that predisposing genetic factors might play a part in the development of the tumors., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Hidroacanthoma simplex (HAS) is a rare benign eccrine adnexal tumor. HAS is sometimes clinically or pathologically misdiagnosed as squamous cell carcinoma in situ (Bowen's disease; BD), seborrheic keratosis (SK) or other adnexal tumor. To date, there has never been a report focusing on dermoscopic features to distinguish HAS from BD and SK. We found the following dermoscopic findings to be characteristic of HAS: fine black dots/globules (75% of cases) and fine scales arranged annularly (100% of cases). In contrast, glomerular vessels, which are typically observed in BD, were not seen in any of the four cases. Cerebriform appearance and milia-like cysts, which are typically observed in SK, were also not seen in any of the four cases. The existence of "scattered fine black dots/globules" and "fine scales arranged annularly", and the absence of the glomerular vessels, may contribute to precise diagnosis of HAS. Even though HAS resembles BD or SK clinically, it can be distinguished from these by the characteristic dermoscopic features., (© 2015 Japanese Dermatological Association.)

Nevus sebaceus (NS) is a congenital, benign, hamartomatous lesion and it is possible to see several benign or malignant tumors accompanying it. One of these is the poroma, which is very rare, and has only been reported twice before, in the English literature. In this paper, we presented two new cases of NS. One of them was a 40-year-old male who presented with a congenital skin lesion on his temporoparietal region. This lesion was composed of four different lesions, including NS, poroma, basal cell carcinoma (BCC), and verruca vulgaris. The second patient was a 41-year-old male presenting with a yellow-brown patch on the scalp. This lesion was comprised of NS and BCC. In addition to these presentations, we discussed the differential diagnosis between BCC and trichoblastoma, both of which are likely to be seen with NS. For this purpose, we recommended an immunohistological panel, which may be useful for differentiating these two morphologically similar lesions.

Eccrine poroma is a benign adnexal tumour of the uppermost portion of the intraepidermal eccrine sweat gland duct and acrosyringium. Eccrine porocarcinoma is the malignant phenotype arising from the intraepidermal portion of the eccrine sweat gland duct epithelium or from pre-existing eccrine poroma. Both commonly occur in the palms or sides of the feet; these areas have a high concentration of eccrine sweat glands. We describe two respective cases of benign and malignant eccrine poroma on the scrotum, which entailed good excisional results.

Merkel cell carcinoma (MCC) has been reported in association with other types of cutaneous neoplasms within the same lesion, including squamous cell carcinoma, Bowen's disease, actinic keratosis, follicular cysts, trichoblastoma and lentigo maligna, among others. However, the association of MCC and sweat gland tumors has never been described in the literature. We report two unique cases of MCC that developed within cutaneous poromas. A 56-year-old male (Patient 1) and an 81-year-old female (Patient 2) presented with nodules on the upper arm and lower back, respectively. Histopathologic study of both cases revealed a tumor in the dermis composed of poroid and cuticular cells intermingled with a proliferation of small round cells that showed characteristic histopathological and immunohistochemical features of MCC. In both cases, the two neoplasms were tightly admixed and distinct, suggesting that the MCC could have developed within a previously existing poroma. No morphological features of transition between the two tumors were seen. Neoplastic cells of MCC expressed immunoreactivity for chromogranin, synaptophysin, neuron-specific enolase, CAM 5.2 and cytokeratin 20, the last two markers showing the characteristic paranuclear dot-like pattern. In contrast, the poroma cells only expressed cytokeratin MNF116. Metastatic deposits were not identified in the regional lymph nodes or distantly., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objective: To investigate the clinicopathological features and the differential diagnosis of poroma and porocarcinoma., Methods: Histopathological characteristics and clinical data of 35 cases of poroma and 10 cases of porocarcinoma were analyzed retrospectively., Results: The average age of 35 patients of poroma was 48 years. The average age of 10 patients of porocarcinoma was 65 years. Both poroma and porocarcinoma occured most frequently on the scalp and face,as well as the extremities. Histologically, cases of poroma were divided into three subtypes, including classic poroma (23 cases), hidroacanthoma simplex (3 cases) and dermal duct tumor (9 cases). Residual foci of benign poroma were found in all cases of porocarcinoma, most of which were classic poroma. The malignant components showed severe dysplasia and/or stromal infiltration., Conclusion: The diagnosis of poroma and porocarcinoma is mainly based on the microscopic characteristics. An invasive architectural pattern and/or significant cytologic pleomorphism are the most important clues for the diagnosis of porocarcinoma. Neither focal mitotic activity nor the presence of necrosis was the diagnostic feature of porocarcinoma. Malignant transformation can occur in some cases of long existing poroma with recent, rapid tumor enlargement.

A 68-year-old woman presented for evaluation of a large, red-brown plaque on her left buttock with irregular borders and prominent overlying verrucous changes. The plaque had been present since childhood but over a three-year period had been enlarging with increasing nodularity and easy bleeding with trauma. Histopathologic examination demonstrated an enlarged papillated and polypoid heterogeneous lesion. In part of the specimen, there are bulbous aggregates of small squamous cells with foci of eccrine ductal differentiation. There are other areas with horn pseudocysts, hypergranulosis, and compact orthokeratosis with parakeratosis. There are scattered enlarged heavily pigmented melanocytes, some of which have long and thick dendrites. This collision tumor consisted of an eccrine poroma, a seborrheic keratosis, and a viral wart. The clinical and histopathologic features of collision tumors and poromas are reviewed.

Eccrine poromas are rare, benign adnexal tumors that often occur as solitary papules. Rarely, eccrine poromas can present as multiple lesions, which is referred to as eccrine poromatosis. We report a case of eccrine poromatosis occuring on the palms and soles occuring after chemotherapy in a patient with a history of acute myeloid leukemia.

Poroma is a benign adnexal neoplasm of the terminal sweat gland duct. Although poromas have traditionally been thought to originate from the eccrine sweat gland, there have been cases of apocrine etiology as well. Eccrine and apocrine poromas typically present as erythematous or flesh-colored nodules on the palms and soles. As these features overlap with a multitude of differential diagnoses, it is imperative to have a firm understanding of the characteristics that make the diagnosis of poroma. In addition, the malignant counterpart to the poroma, the eccrine porocarcinoma, manifests in a similar nonspecific fashion. Case studies and literature reviews have contributed immensely to our present knowledge of poroma and porocarcinoma. Given the rarity of these neoplasms, however, there remains a relative paucity of information on atypical presentations and rates of malignant transformation. In this article, the epidemiology, clinical presentation, diagnosis, and management of poroma and porocarcinoma will be reviewed. This systematic approach may serve as a guide in navigating the diagnostic dilemma of these rare cutaneous lesions., (© 2014 The International Society of Dermatology.)

Poromas were originally classified as eccrine tumors which predominantly consist of poroid ductal cells and differentiate in the direction of sweat gland ducts. However, there have now been many reports on poromas with additional differential characteristics differentiating in the direction of sebaceous and/or apocrine glands and/or hair follicles. These tumors have been termed apocrine poromas. Multilineage differentiation within a poroma can be explained by the embryological association of the sweat duct with the so-called folliculo-sebaceous-apocrine unit. The clinical and histopathological features of apocrine poromas are reviewed in comparison to classical eccrine poromas by taking into account seven own cases of apocrine poroma and a review of the literature. It is important for histopathologists not to confuse apocrine poroma with other tumors with multilineage differentiation. Apocrine poroma needs to be distinguished from sebaceoma and from basal cell carcinoma with sebaceous differentiation, in particular, because these tumors have therapeutic consequences for the patient. The main histopathological differences between apocrine poroma, sebaceoma and basal cell carcinoma with sebaceous differentiation are explained.

Lumican, a member of the small leucine-rich proteoglycan family, regulates the assembly and diameter of collagen fibers in the extracellular matrix of various tissues. The lumican expression correlates with pathological conditions and the growth and metastasis of various malignancies. In cutaneous neoplasms, the lumican expression is lower in advanced-stage malignant melanomas that invade the dermis than in early-stage melanomas. Furthermore, we have recently reported that the expression pattern of lumican is different from that of actinic keratosis and the Bowen disease. Lumican is positive in the poroid cells of intraepidermal sweat ducts; therefore, we examined the expression patterns of lumican in acanthotic-type seborrheic keratosis and Pinkus-type poroma followed by clonal-type seborrheic keratosis and hidroacanthoma simplex. The neoplastic cells of acanthotic-type seborrheic keratosis exhibited positive immunostaining in only 1 of 31 cases (3.23%), whereas the poroid cells of Pinkus-type poroma exhibited positive immunoreactivity in 26 of 28 patients (92.8%). In the hidroacanthoma simplex cases, lumican was expressed in poroid cells forming intraepidermal nests in 22 of 28 patients (78.6%), whereas the neoplastic cells in most cases of clonal-type seborrheic keratosis were negative for lumican. In some seborrheic keratosis cases that were positive for lumican in neoplastic cells, lumican was observed in squamoid cells but not in basaloid cells. Therefore, it is necessary to evaluate the immunoreactivity of lumican in seborrheic keratosis and in basaloid cells. These findings suggest that lumican is a potent differential diagnostic marker that distinguishes hidroacanthoma simplex from clonal-type seborrheic keratosis.

Aim: Pigmented poromas are rarely reported and considered to be more common in non-white people and on non-acral sites. Objective of the present study was to report our cases of pigmented poromas with particular attention to the presence of clinical and/or microscopic evidence of pigmentation, their characteristics and the diagnostic pitfall with other pathologies., Methods: All the histologically confirmed poromas observed from January 1994 to July 2012 were considered. Clinic-epidemiological data were collected. The presence of clinical pigmentation was recorded as well as the presence of melanin pigmentation or melanocytes in the histologic specimens., Results: One hundred and one patients with poromas were collected. All the patients were Caucasians. All the lesions were solitary. Only three patients had a clinically visible pigmented poromas. In eight cases the presence of melanin and melanocytes did not produce a clinically visible pigmentation. All the poromas with pigmentation did not occur on palmo-plantar surfaces., Conclusion: Pigmented poromas may be observed even in Caucasian patients and their clinical aspect mimic basal cell carcinoma and/or melanoma. The presence of pigment visible at the histology may not be observed in the clinical expression. The absence of pigmentation on palmo-plantar location is confirmed in all the reported cases.

Eccrine poroma (EP) is a benign tumor of the eccrine duct. Multiple EPs are defined as eccrine poromatosis (EPS), an uncommon phenomenon. To date there are only eight reported cases of EPS. This review exemplifies the epidemiology, pathogenesis, differential diagnosis, and histology of EP, while reviewing the eight cases of EPS. Six of the eight cases of EPS had a history of immunosuppression from either radiation or chemotherapy. This paper will also emphasize the importance of excision to avoid possible malignancy. Here we present a 73-year-old gentleman with EPS who was also treated with radiation and chemotherapy prior to the onset of the lesions., (© 2013 The International Society of Dermatology.)

Background: Poromas are benign adnexal tumours generally believed to be of eccrine origin, which usually develop on palmoplantar sites. However, it is thought that a percentage of poromas develop on non-palmoplantar or 'unusual' sites., Aim: To review cases of poromas with reference to their clinicoepidemiological characteristics, paying particular attention to the those located on sites other than the palms and soles., Methods: All histologically confirmed poromas seen at our department between 1994 to 2012 were reviewed. The clinicoepidemiological data recorded included age at diagnosis, gender, location, size, colour, and preoperative and pathological diagnoses., Results: In total, 101 poromas were reviewed, corresponding to 0.0058% of all the epithelial skin tumours biopsied in our department. The mean age was 65.05 years (range 30-100 years), and the male to female ratio was 1.52. All the lesions were solitary and asymptomatic, with no sign of bleeding. The most common presentation was a red or reddish lesion, particularly at palmoplantar sites, where 33 (32.7%) of the 101 poromas were located, Poromas found at other affected sites were more usually skin-coloured, and these lesions included 7 neoplasms located in the armpits and 18 on the head and neck. The correct preoperative diagnosis was made in 12 cases of 33 detected poromas (36%), all of which were localized to the palmoplantar surfaces., Conclusions: Based on our experience, we consider that there are no 'unusual' sites for poromas, and palmoplantar poromas were in fact in the minority. Furthermore, some localizations suggest derivation of these palmoplantar poromas from the folliculosebaceous apocrine unit., (© 2013 British Association of Dermatologists.)

We report a case of a 48-year-old Malay female who presented with multiple tumors arising from a large nevus sebaceus on her right parieto-temporal scalp. Histologically, the tumors corresponded to a sebaceoma with carcinomatous change, a poroma and a trichoblastoma. Immunohistochemical staining of the sebaceous tumor with p53 showed strong within the areas of carcinomatous change, while there was negative to weak staining within the sebaceoma-like areas. A discussion on the potential secondary neoplasms from a nevus sebaceus ensues, with a review of this literature on multiple tumors from a nevus sebaceus., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Dermal duct tumor is a rare, benign tumor. Clinically, dermal duct tumor presents as a firm papule, plaque or nodule, particularly on the lower limbs or head and neck region. Dermal duct tumor is been classified as poroma. Poroma can have divergent differentiation, but showing prominent ductal and sebaceous differentiation is rare. We present a case of dermal duct tumor with prominent ductal and sebaceous differentiation arising in the scalp. A 45-year-old man with a painless slow-growing, elevated, brownish nodule on his scalp of 7-year duration was admitted to our hospital. Histopathology revealed dermal duct tumor. The neoplasm also showed prominent ductal and sebaceous differentiation.

A 42-year-old man presented with a rapidly growing nodule on his right cheek. Except for some itching, it was asymptomatic. The tumor was excised with 3-4 mm safety margin. The clinical differential diagnostic considerations included pyogenic granuloma, amelanotic melanoma, basal cell carcinoma and eccrine poroma. An eccrine poroma is a rare tumor derived from the eccrine sweat gland. Hormonal disturbances, trauma, immunosuppression, actinic damages and radiotherapy have been suggested as possible etiologic factors; however, the exact pathophysiology remains unclear.

Poroma is a rare, benign, appendage tumor. Clinically, it presents as a solitary, slowly growing tumor situated mostly on the palms and soles of adults. Occasionally, poroma mimics malignant tumors. Histological examination reveals aggregations of poroid cells extending into the epidermis. Dermoscopy may be useful in some cases. Treatment is by surgical excision. We report a case of a typical clinical and histopathological presentation in a 26-year-old woman and emphasize the importance of this lesion in the differential diagnosis of other tumors on the palms and soles.

Eccrine poroma frequently occurs as a solitary tumour, and only a few reports have described the occurrence of multiple lesions. Multiple eccrine poromas, or eccrine poromatosis, may occur in patients who have undergone radiotherapy and/or polychemotherapy. We report here four cases of multiple eccrine poromas in patients who were either undergoing, or had undergone, intensive chemotherapy (from 6 months to 16 years prior to onset). Three patients had non-Hodgkin's lymphoma and one had malignant fibrous histiocytosis. The number of lesions varied from 3 to > 20 in each patient, and all the lesions occurred on non-irradiated skin. The histopathological features were consistent with those of eccrine poroma, Pinkus type. In addition to radiation therapy, intensive chemotherapy may play a role in the pathogenesis of multiple eccrine poromas even many years after treatment.

A poroma is a benign epithelial neoplasm that most commonly presents as a solitary papule on the palm or sole. We report the case of a 25-year-old male, with a history of acute myelogenous leukemia, who developed multiple poromas on the feet. Poromatosis - the occurrence of multiple poromas - has been described in six adults and one child; it appears to be more prevalent in patients with a history of lymphoproliferative disorder or radiation exposure.