Benign Melanocytic Proliferations Research Articles

CLINICAL CASE OF RECURRENT NEVUS

Abstract. Introduction. Recurrent nevus is a benign proliferation of melanocytes that occurs at the site of non-radical removal of a previously existing nevus. Recurrence rates range from 0.3% to 28% and most often occur within 6 weeks to 6 months after removal. Clinically recurrent nevus is characterized by uneven pigmentation with uneven edges in the area of the scar.
 Walton et al. began researching the phenomenon of recurrent nevus in 1957. In 1975, Kornberg and Ackerman reported that a pigmented recurrent nevus can resemble superficially spreading melanoma both clinically and histologically, and proposed the term pseudomelanoma to describe this benign phenomenon. Currently, the term is rarely used, but it motivates a thorough examination of patients with such a problem.
 Case presentation. Patient A. complained about the presence of a formation in the area of the outer surface of the right forearm, which has existed for many years, it was injured several times, but has recently changed the colour. On examination, a nodule up to 0.5 cm in size, heterogeneously pigmented, with peripheral erythema was found in the indicated place. During dermoscopy, chaotic unevenly distributed pigmentation, consisting of dots, globules, forming a cellular structure in a scattered manner is determined, zones of segmental radial lines are present as well. The vascular pattern in the central part of the formation is not defined, on the periphery it is represented by slightly noticeable point vessels. Digital post-processing using machine learning technology was carried out to improve visualization of blood supply. Multiple point, curved, and convoluted vessels with few branches around the formation, and several central vessels in the pigment cells are determined. Surgical removal of the tumor was performed with involvement of the erythema zone, taking into account the peculiarities of pigmentation and vascular pattern. The pathogistological structure is presented in the photomicrograph. The epidermis has a typical structure, with areas of slight acanthosis; hyperpigmentation of the basal layer is also observed. In the dermis, foci of brown pigment deposition, single lymphocytes, there are areas of intradermal lobular-horizontal fibrosis with angiomatosis and scattered lymphocytic infiltration. Taking into account the clinical data, there is a recurrence of a melanocytic nevus on the background of a skin scar (Recurrent neavus).
 Teaching point. Dermoscopy allows obtaining additional data for the differential diagnosis of recurrent nevus and recurrent melanoma. A recurrent nevus is characterized by relative symmetry of formation and a pattern of segmental radial lines. The formation is limited to the area of the scar and does not go beyond it. Also, in the case of recurrent melanoma, a continuous growth in dynamics and a later appearance of recurrence from the moment of intervention will be obvious.
 Conclusions. As clinical practice demonstrates, under certain circumstances, recurrent pigmentation can be observed in cases of nevi that have been traumatized. It will be visible both dermoscopically and pathohistologically. Sometimes it is difficult even for experts to distinguish between a highly irritated nevus and a melanoma.

Congenital Naevus: Case Report of an Atypical Atrial Location

Congenital naevi are a benign proliferation of melanocytes. Present at birth or appearing in the first weeks of life, they have the appearance of light to dark brown lesions, sometimes bluish, more or less hairy. It is a non-hereditary mosaic pathology. They are due to postzygotic somatic mutations involving key proteins in the mitogen-activated protein kinase pathway, mainly NRAS and BRAF. Its prevalence is estimated to be between 1 and 3% of newborns. This disease can affect any part of the skin. There are 3 types of naevi: small, medium and large naevi then called giant. The objective was to discuss the clinical and therapeutic aspect of a congenital auricular naevus of medium size. We report the case of an 18 years old girl presenting a sessile tumefaction at the level of the concha of the right auricle that appeared from birth, firm, rough, unique, about 5 cm in diameter, homogeneous in color, pigmented, hairy, painless to palpation, apyretic sometimes pruritic without any other associated sign. The diagnosis of benign congenital naevus was clinically made after confirmation by the dermatologist. Surgical removal was performed. The postoperative course was simple with complete healing after one month. The middle congenital naevus is a benign tumor linked to a genetic variation of low incidence, which is all the more rare as it is located on the ear, thus having a significant psychological impact due to its often unsightly appearance. The diagnosis of this genodermatosis is essentially clinical. When it is an isolated nodule, as in our study, total surgical removal is a good alternative with simple after-effects and an almost non-existent risk of malignant transformation.

Standardized Computer-Assisted Analysis of PRAME Immunoreactivity in Dysplastic Nevi and Superficial Spreading Melanomas.

PRAME (PReferentially expressed Antigen in MElanoma) is a cancer testis antigen that is frequently expressed in melanoma compared to benign melanocytic proliferations and nevi. However, the interpretation of the intensity and distribution of PRAME immunostaining is not standardized a lot, which makes interpretation difficult. PRAME-stained histological slides of superficial spreading melanomas (SSM) and dysplastic nevi (DN) were digitized and analyzed using the digital pathology and image platform QuPath. t-tests and ROC AUCs were performed with SPSS. A p-value of <0.05 was used for statistical significance, and a ROC AUC score of >0.8 was considered a good result. A cut-off score was defined in an evaluation cohort and subsequently analyzed in an independent validation cohort. In total, 81 PRAME-stained specimens were included. The evaluation cohort included 32 (50%) SSM and 32 (50%) DN, and the mean of PRAME-positive cells/mm2 for the entire lesion was 455.3 (SD 428.2) in SSM and 60.5 (SD 130.1; p < 0.001) in DN. The ROC AUC of PRAME-positive cells of the entire lesion was 0.866, and in the epidermis it was 0.901. The defined cut-off score to distinguish between DN and SSM was 97.67 cells/mm2. In the validation cohort, 16 out of 17 cases (94.1%) were correctly classified by the cut-off score. The computer-aided assessment of PRAME immunostaining is a useful tool in dermatopathology to distinguish between DN and SSM. Lesions with a moderate expression and indifferent morphologic features will remain a challenge for dermatopathologists.

Analysis of dermoscopic changes of blue nevi on digital follow-up: A 21-year retrospective cohort study.

Blue nevi are benign dermal melanocytic proliferations that are often easy to recognize clinically. Rarely, these lesions can display atypical features, suggesting the presence of a malignant blue nevus or mimicking cutaneous metastases of melanoma. To describe the clinical evolution of blue nevi over time and to assess the need for monitoring these lesions. We conducted a retrospective cohort study of 103 patients who were followed between December 1998 and November 2019. An artificial intelligence algorithm was used to identify blue nevi from the databases of two digital epiluminescence devices. Changes in the area of each lesion were calculated with a segmentation neural network. We included 123 blue nevi from 103 patients. Most of the lesions segmented, 99 (91.7%), were considered stable. Of the 9 (8.3%) growing blue nevi identified, 2 (1.85%) showed significant growth. The studied growing blue nevi turned out to be cellular blue nevi, presented with a low tumour mutation burden and GNAQ c.626A>T alteration was identified in both lesions. Some clinical variants of blue nevi might not be included. Most blue nevi remain stable during their evolution. Rarely, they can show progressive growth, although histopathological or molecular signs of malignancy have not been identified.

Diagnostic test accuracy meta-analysis of PRAME in distinguishing primary cutaneous melanomas from benign melanocytic lesions.

PRAME is a novel immunohistochemical marker that aids the diagnosis of melanocytic lesions. Diffuse PRAME positivity suggests melanoma, whereas benign naevi are negative or only weakly positive. However, the factual diagnostic accuracy of PRAME is not well established. Moreover, some studies have suggested that the threshold of 3+/50% positive cells may be more useful in practice than the most widely used cut-off (4+/75% of positive cells). Hence, we performed a systematic review and diagnostic accuracy meta-analysis to evaluate sensitivity, specificity, likelihood ratios and optimal threshold for PRAME in distinguishing benign melanocytic proliferations from melanomas. Twenty-six studies were enrolled into the meta-analysis. A total of 2915 melanocytic lesions were analysed. The optimal threshold for PRAME positivity was estimated at 3.11, which translates into 3+ in practice. Sensitivity and specificity calculated from SROC at the 3+ threshold were 0.735 (0.631-0.818) and 0.915 (0.834-0.958), respectively, compared to 0.679 (0.559-0.957) and 0.957 (0.908-0.981) at the 4+ cut-off. In subgroup analysis, the spitzoid subgroup was characterised by the lowest sensitivity and diagnostic odds ratio of PRAME. Our findings indicate that PRAME immunohistochemistry may serve as an ancillary marker to support the diagnosis of melanoma. Nevertheless, the accuracy of PRAME may be lower in spitzoid neoplasms. Our meta-analysis suggests that the 3+/50% threshold might be more useful in practice than the 4+/75% cut-off, as it shows higher sensitivity with retained satisfactory specificity.

PRAME Immunohistochemical Expression and TERT Promoter Mutational Analysis as Ancillary Diagnostic Tools for Differentiating Proliferative Nodules From Melanoma Arising in Congenital Nevi.

Proliferative nodules (PNs) are benign melanocytic proliferations that typically develop within congenital melanocytic nevi. These tumors have overlapping histological features with melanoma. Ancillary immunohistochemistry and genomic sequencing are often used in diagnostically challenging cases. To assess the utility of preferentially expressed antigen in melanoma (PRAME) immunoreactivity and telomerase reverse transcriptase (TERT) promoter mutation analysis in distinguishing PNs from melanoma arising in congenital nevi cases. Twenty-one PNs and 2 melanomas arising in congenital nevi were immunohistochemically stained with PRAME. Cases with adequate tissue were also assessed for TERT promoter mutations through sequencing studies. The positivity rates in the PN cases were compared with those of the melanomas. Two of 21 PN cases were diffusely positive for PRAME (≥75% of the tumor cells positive). Two of 2 melanomas arising in congenital nevus cases were also diffusely PRAME positive. The difference was statistically significant using a Fisher exact test. None of the tumors harbored TERT promoter mutations. PRAME immunohistochemical marker may have diagnostic value in distinguishing diagnostically challenging PNs from melanoma, but diffuse expression is not specific for melanoma.

The Complex Interplay between Nevi and Melanoma: Risk Factors and Precursors.

One effort to combat the rising incidence of malignant melanoma is focused on early detection by the clinical and dermoscopic screening of melanocytic nevi. However, the interaction between nevi, which are congenital or acquired benign melanocytic proliferations, and melanoma is still enigmatic. On the one hand, the majority of melanomas are thought to form de novo, as only a third of primary melanomas are associated with a histologically identifiable nevus precursor. On the other hand, an increased number of melanocytic nevi is a strong risk factor for developing melanoma, including melanomas that do not derive from nevi. The formation of nevi is modulated by diverse factors, including pigmentation, genetic risk factors, and environmental sun exposure. While the molecular alterations that occur during the progression of a nevus to melanoma have been well characterized, many unanswered questions remain surrounding the process of nevus to melanoma evolution. In this review, we discuss clinical, histological, molecular, and genetic factors that influence nevus formation and progression to melanoma.

Stardust Pattern as Evolution of Pigmented Spitz Nevi During Childhood.

Spitz nevi (SN) are benign melanocytic proliferations frequently occurring in children. Some pigmented SN with a starburst pattern evolve into the "stardust" one, which is characterized by a central, black to gray, hyperpigmented area and remnants of a brown network at the periphery. These dermoscopy changes are often the first alert to induce excision. The aim of this study is to enlarge the case series of stardust SN in children, in order to increase confidence with this new dermoscopic pattern and reduce unnecessary excisions. This retrospective observational study was conducted with SN cases received from IDS members. The inclusion criteria were: clinical and/or histopathologic diagnosis of Spitz naevus with starburst appearance in children <12 years old, availability of a dermoscopic image at baseline and after follow-up of at least 1 year, availability of patient data. The dermoscopic images and their changes over time were assessed by three evaluators in consensus. 38 SN were enrolled, with a median age of 7 years and a median FUP duration of 15,5 months. Comparing the evolution with time of FUP, no significant differences were found between growing and involuting lesions in terms of patient age and sex, location and palpability of lesions. The long follow-up reported in our study could really support the concept of benignity of changing SN. A conservative approach is acceptable for nevi showing the stardust pattern, because it may be considered a physiological evolution of pigmented Spitz nevus, and urgent surgeries could be avoided.

630 Cdk2: A marker for invasive melanoma

Background: Although cyclin-dependent kinase 2 (CDK2) is known to be upregulated in certain cancers, its spatial expression pattern in melanocytic tumors has remained unknown. Objective: To characterize CDK2 expression in benign and malignant melanocytic proliferations. Methods: We performed CDK2 immunohistochemistry (IHC) on normal skin and a tumor panel comprising over 200 congenital nevi, dysplastic nevi, melanomas in situ, and invasive melanomas. We recorded their staining patterns, intensities, and compared these to expression of melanoma marker PRAME (Preferentially expressed Antigen in Melanoma).

Cyclin D1 and PRAME expression in distinguishing melanoma in situ from benign melanocytic proliferation of the nail unit

BackgroundDistinguishing benign lesion from early malignancy in melanocytic lesions of the nail unit still remains a diagnostic challenge, both clinically and histopathologically. While several immunohistochemistry (IHC) stainings have been suggested to help discriminate benign subungual melanocytic proliferation (SMP) and subungual melanoma in situ (MIS), the diagnostic utility of IHC staining for cyclin D1 and PRAME has not been thoroughly investigated in melanocytic lesions of nail unit.MethodsThis retrospective study included cases of benign SMP and subungual MIS confirmed by biopsy at Asan Medical Center from January 2016 to December 2020. Cases of melanocytic activation without proliferation and melanoma where dermal invasion was identified were excluded. Cyclin D1 and PRAME expression was assessed by counting proportion of melanocytes with nuclear positivity under 200x magnification.ResultsA total of 14 patients with benign SMP and 13 patients with subungual MIS were included in this study. 11 patients with benign SMP (71.4%) and 5 patients with subungual MIS (38.5%) showed > 60% nuclear immunostaining for cyclin D1, respectively. While 13 patients with benign SMP (92.9%) showed totally negative staining for PRAME, 10 patients with subungual MIS (76.9%) exhibited > 50% nuclear immunostaining for PRAME. Using the cutoff of 10%, PRAME exhibited good overall discrimination between benign SMP and subungual MIS (AUC = 0.849, 95% CI = 0.659–0.957).ConclusionsThis study suggests that PRAME IHC staining as a reliable discriminator in distinguishing subungual MIS from benign SMP.

Hypopigmented variant of intraoral common blue nevus. A rare entity

<h3>Objectives</h3> Blue nevus (BN) represents a clinicopathologically distinctive subset of benign melanocytic proliferations that may affect the oral mucosa. While diagnosis of conventional BN is usually straightforward, some of its rare variants may cause significant overlap with other entities, causing diagnostic pitfalls. Herein we present a case of hypopigmented variant of common BN and discuss the diagnostic challenges. <h3>Findings</h3> A 52 year-old male of unremarkable medical history was referred for the evaluation of a painless palatal lesion of unknown duration. The clinical examination revealed a well-circumscribed, slightly elevated lesion of normal hue with bluish halo involving the hard palate. With a provisional diagnosis of BN an excisional biopsy was decided. Histopathologically, a proliferation composed of scattered elongated, finely branching melanocytes, located deeply within the lamina propria with non-infiltrating pattern and associated with a variably desmoplastic stroma, was observed. Cytoplasmic pigmentation was detected only in a small subset of dendritic processes after serial sectioning. Minimal cytologic atypia and mild nuclear pleomorphism were also present in the absence of mitotic activity. In order to rule out malignant melanocytic tumors, especially desmoplastic melanoma, extensive immunohistochemical examination was performed. Melanocytes were strongly and diffusely positive for Melan-A, HMB-45, SOX-10, S-100, p16, and vimentin. The proliferation index Ki-67 was <5%. A final diagnosis of hypopigmented common BN was rendered. No signs of recurrence were noted during follow-up. <h3>Conclusions</h3> To this date, few cases of BN with minimal or absent pigmentation have been reported in the literature. However, this pattern is extremely rare in lesions affecting the oral mucosa. Hypopigmented BN lesions require careful evaluation to be distinguished primarily from desmoplastic melanoma. Immunohistochemistry may be helpful, especially when tumors with atypia, pleomorphism, infiltrative pattern and/or mitoses are encountered.

Blue Nevus Involving Minor Salivary Gland

Blue nevus is a benign melanocytic tumor that commonly occurs on the skin. It appears as a solitary, well-demarcated, dark blue nodule or smooth-surfaced macule. Blue nevus has been reported in the lymph nodes, parotid, and prostate glands. In the oral cavity, blue nevus accounts for one-third of all oral mucosal melanocytic nevi, with the palate being the most common location. Microscopically, the blue nevus is composed of a benign proliferation of bipolar dendritic melanocytes in the deeper layers of the connective tissue. The distinctive blue hue is attributed to the deep location of the melanocytes and the Tyndall effect. To our knowledge, this is the first article to document blue nevus involving minor salivary glands. One month following the excisional biopsy and thereafter, no evidence of recurrence was noted. The diagnosis was established only after histopathological examination of the biopsy specimen. Microscopic examination of oral pigmented lesions is necessary for a conclusive diagnosis and to rule out neoplasms such as melanoma that can clinically mimic blue nevus.

Bilateral Diffuse Uveal Melanocytic Proliferation Secondary to Rectal Adenocarcinoma: A Case Report and Literature Review.

Background: Bilateral diffuse uveal melanocytic proliferation (BDUMP) is a rare paraneoplastic intraocular syndrome that causes progressive visual loss in patients, and is associated with an underlying malignancy. Recently, the incidence of BDUMP has increased with the prolonged life expectancy of oncology patients.Case Presentation: We report a case of a 68-year-old man with significant visual loss in both eyes. The patient presented with a diffusely thickened choroid and ciliary body, extremely shallow anterior chamber, increased intraocular pressure, and cataract formation, accompanied by exudative retinal detachment in both eyes. He underwent a pars plana vitrectomy and choroidal biopsy, which revealed benign proliferation of melanocytes. A small amount of subretinal fluid persisted, and uveal thickness persisted in the early postoperative period. During the 1-year follow-up assessment, he underwent rectal tumor resection, and was pathologically diagnosed with rectal adenocarcinoma. Six months after the rectal tumor resection, the subretinal fluid was completely absorbed and the retina had reattached. The thickness of both the ciliary body and choroid had significantly decreased.Conclusion: This case report describes a rare paraneoplastic intraocular syndrome, BDUMP, which was associated with rectal adenocarcinoma. Treatment for the primary malignancy gradually improved the visual symptoms and signs.

PRAME immunohistochemistry is useful in the evaluation of conjunctival melanomas, nevi, and primary acquired melanosis.

Many dermatopathologists find conjunctival melanocytic proliferations challenging because they are rare relative to their cutaneous counterparts and have nuanced morphology and nomenclature. PRAME immunohistochemistry has been widely adopted for distinguishing cutaneous nevi from melanoma, but limited data exist assessing its utility in evaluating conjunctival specimens. In particular, it is uncertain whether it can predict the risk of melanoma progression in primary acquired melanosis (PAM). Thirty clinically annotated cases (two melanomas, three PAM with atypia, seven PAM without atypia, 15 nevi, two combined nevi, and a diagnostically challenging nevus with atypical features) were retrospectively evaluated with PRAME. Strong, diffuse PRAME expression was present in melanomas and PAM with high-grade atypia, but not in PAM with low-grade atypia, PAM without atypia, or nevi. Scattered, faintly PRAME-positive intraepithelial melanocyte nuclei were identified in six nevi. A clonal nevus and nests of heavily pigmented type-A melanocytes in two additional nevi had cytoplasmic staining. PRAME was useful for distinguishing melanoma and its probable precursors from benign conjunctival melanocytic proliferations in our cohort. The data alert us to two diagnostic pitfalls in nevi: scattered, PRAME-positive intraepithelial melanocytes and cytoplasmic PRAME staining in type-A melanocytes and melanophages. Larger scale investigations are warranted to further substantiate these promising findings.

A Case of Blue Nevus of the Nasal Septum

Blue nevus (BN) is a blue- or black-colored benign melanocytic proliferation that commonly occurs on the dorsal surface of the hands and feet or in the head and neck region. However, BN arising from the sinonasal mucosa is extremely rare. BN is usually asymptomatic and small in size. Based on the pigmentation of BN, sinonasal malignant melanoma should be considered in the differential diagnosis of BNs in this region. We herein report a case of BN of the nasal septum. Histopathologic examination revealed the presence of heavily pigmented, spindle-shaped melanocytic cells within the stromal tissue. On immunohistochemical analysis, BN cells were positive for S-100 and HMB-45. Due to the few reported cases of sinonasal BN and challenging location, complete resection, biopsy, and adequate follow-up are recommended.

ORAL JUNCTIONAL MELANOCYTIC NEVUS ASSOCIATED WITH LENTIGINOUS HYPERPLASIA: A CASE REPORT IN A PEDIATRIC PATIENT

Oral melanocytic nevi (OMNs) are uncommon benign melanocytic proliferations. Clinically, OMNs are small, well-circumscribed, flat lesions, but not uncommonly appear as slightly raised papules. They can be brown, bluish-gray, or almost black, and occasionally non- pigmented. Regarding the OMN etiology and pathogenesis, most studies have focused on its cutaneous counterpart. We present a case of OMN in a pediatric patient. A 4-year-old male was referred presenting a dark macule with regular borders, measuring 6 mm in greater diameter, located on the right retromolar pad, with a time of evolution of 15 days. The clinical diagnoses were melanotic macule and OMN. After excisional biopsy, the microscopic examination revealed junctional melanocytic nevus with lentiginous hyperplasia containing focal melanocytic atypia. After 4 months of follow-up, there is no recurrence or alteration. Thus, lentiginous junctional melanocytic proliferation with focal atypia may be observed in OMN, which should be interpreted with caution, especially in pediatric patients. Oral melanocytic nevi (OMNs) are uncommon benign melanocytic proliferations. Clinically, OMNs are small, well-circumscribed, flat lesions, but not uncommonly appear as slightly raised papules. They can be brown, bluish-gray, or almost black, and occasionally non- pigmented. Regarding the OMN etiology and pathogenesis, most studies have focused on its cutaneous counterpart. We present a case of OMN in a pediatric patient. A 4-year-old male was referred presenting a dark macule with regular borders, measuring 6 mm in greater diameter, located on the right retromolar pad, with a time of evolution of 15 days. The clinical diagnoses were melanotic macule and OMN. After excisional biopsy, the microscopic examination revealed junctional melanocytic nevus with lentiginous hyperplasia containing focal melanocytic atypia. After 4 months of follow-up, there is no recurrence or alteration. Thus, lentiginous junctional melanocytic proliferation with focal atypia may be observed in OMN, which should be interpreted with caution, especially in pediatric patients.

Clinicopathological study of blue nevi of the gastrointestinal (GI) tract: first case series

AimBlue nevus (BN) is a benign melanocytic proliferation that is typically cutaneous. Extracutaneous BN is infrequent and is reported in the mucosa of various organs. Gastrointestinal (GI) tract BN is...

Clinical evolution of Spitz nevi

Nevus Spitz is a benign melanocytic proliferation, first described in 1948 by Sophie Spitz as a childhood melanoma. Initially, it was described as an erythematous papule or node, but further studies of the Spitz nevus proved that in 71-92% cases it is a pigmented formation. This pigmentation is often quite intense due to the rapid growth of the formation, which leads to the need for differential diagnosis with skin melanoma. After all, dermatoscopy can be used for this purpose and, when applying this research method, typically a pattern of an exploding star formed by streaks of linear pigmentation and symmetrically located pigment globules placed in the peripheral zone can be revealed. In case of non-pigmented Spitz nevus, spot vessels and reticular depigmentation are visualized. Both pigmented and non-pigmented forms of Spitz nevus in the process of evolution can regress partially or completely. Several clinical cases of different types of spitzoids, both typical and atypical, based on the non-clinical, dermatoscopic and histological diversity of the Spitz nevi, have been demonstrated in the article. Their macroscopic and dermatoscopic features as well as probable signs of dynamic changes are indicated in order to facilitate their recognition by other specialists.

Compound Clear Cell Sarcoma of the Skin-A Potential Diagnostic Pitfall: Report of a Series of 4 New Cases and a Review of the Literature.

The proliferation of cells with melanocytic lineage and a nested pattern has traditionally been regarded as a characteristic feature of a wide range of benign and malignant melanocytic proliferations. Herein, we report a series of 4 clear cell sarcomas, including 3 primary cutaneous and 1 metastatic to the skin, associated with a clear-cut intraepidermal proliferation of tumor cells representing a serious potential diagnostic pitfall. All patients were male individuals, aged from 17 to 71 years (mean: 42 y). The size of the tumors ranged from 8 to 55 mm (mean: 22.2 mm, median: 13 mm). Two tumors arose on a lower extremity and 1 each on the scalp and chest. Cutaneous metastasis developed on the limb proximal to the amputation site. Histologically, all tumors were variably circumscribed nodular or multinodular proliferations within the dermis, focally extending into the subcutis. They were composed of nests and fascicles of pale spindled and epithelioid cells with finely granular or pale cytoplasm, elongated nuclei with a single prominent nucleolus, featuring mild nuclear pleomorphism, and surrounded by delicate fibrous septa. Scattered wreath-like giant cells were present in all cases. Mitotic activity was low (mean and median: 3.5 mitoses/mm). The intraepidermal component consisted in all 4 cases of nests of tumor cells localized at the dermal-epidermal junction. Nests were well-defined and composed of spindled or epithelioid cells with irregular hyperchromatic nuclei, prominent nucleoli, and scant to moderately abundant eosinophilic to pale cytoplasm. Lentiginous proliferation of epithelioid tumor cells was coupled with focal upward migration of isolated tumor cells in a single case. By immunohistochemistry, all tumors were S100 protein, melan A, and HMB45 positive. By fluorescence in situ hybridization analysis, 3 tumors displayed rearrangements in the EWSR1 gene, whereas reverse transcriptase polymerase chain reaction confirmed EWSR1(e8)/ATF1(e4) translocation in the remaining case. In conclusion, an epidermal component in primary cutaneous clear cell sarcomas, or cutaneous metastasis of the tumor, is exceptional and represents a potential diagnostic pitfall. Careful attention to the salient morphologic features in the dermal component of the tumor, as well as confirmation of EWSR1 gene rearrangement by fluorescence in situ hybridization or reverse transcriptase polymerase chain reaction, is necessary for correct recognition of the tumor and to avoid erroneous diagnosis of a benign or malignant melanocytic proliferation.

Conjunctival Melanoma Targeted Therapy: MAPK and PI3K/mTOR Pathways Inhibition.

To analyze the activity of mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinases/mechanistic target of rapamycin (PI3K/mTOR) pathways in benign and malignant conjunctival melanocytic proliferations and explore whether specific inhibitors can suppress growth of conjunctival melanoma (CJM) cells. The presence of a BRAF V600E mutation and activation of ERK, MEK, S6, and AKT were assessed with immunohistochemistry in 35 conjunctival nevi and 31 melanomas. Three CJM cell lines were used: CRMM1, carrying the BRAF V600E mutation; CRMM2, harboring the NRAS Q61L mutation; and T1527A, with a BRAF G466E mutation. WST-1 assays were performed with a BRAF inhibitor (vemurafenib), two MEK inhibitors (trametinib, selumetinib), a PI3K inhibitor (pictilisib), and a dual PI3K/mTOR inhibitor (dactolisib). The phosphorylation of ERK, MEK, and S6 were tested with western blots and apoptosis with cleaved caspase-3 immunostaining. A BRAF V600E mutation was detected in 42.6% of nevi and in 35.5% of CJM. MEK and ERK activation were higher in CJM, occurring in 62.9% and 45.7% of the nevi and 90.3% and 96.8% of the CJM, respectively. There was also a significant increase in S6 activation in CJM (90.3%) compared with the nevi (20%). CRMM1 was sensitive to trametinib and the PI3K inhibitors but only marginally to vemurafenib. CRMM2 was moderately sensitive to pictilisib, whereas T1527A was resistant to all drugs tested. The MAPK pathway activity in CJM is increased, not only as a consequence of the BRAF V600E mutation. Targeted therapy may be useful for patients with CJM, especially those with activating BRAF mutations, whereas NRAS-mutated melanomas are relatively resistant.