Cellular blue nevus. Clinicopathologic study of forty-five cases

Perineural Infiltration: A Comprehensive Review of Diagnostic, Prognostic, and Therapeutic Implications

ABSTRACT

Perineural infiltration refers to a neoplastic cell involvement in, around, and through the nerves. It is considered as one of the neoplastic dissemination pathways. Thus, its identification is crucial to establish the prognosis of some malignant skin neoplasms, such as squamous cell carcinoma, and explains the locally aggressive behavior of cutaneous neoplasms, such as microcystic adnexal carcinoma. We have conducted a review of malignant and benign skin tumors in which perineural infiltration has been described, and we also discuss some histopathological findings that may simulate perineural infiltration.

Invasive cellular blue nevus in the cervical spine: A case report

INTRODUCTION

Cellular blue nevus is an uncommon neoplasm in the spine.

PATIENT CONCERNS

Here, we present a case of a 24 years old male with a 2 months history of numbness in the right upper limb and shoulder.

DIAGNOSIS

Cervical spine and subcutaneous tissue invasive cellular blue nevus.

INTERVENTIONS

The patient underwent C4 laminectomy and partial C3 and C5 laminectomy for total resection of the lesion. Histopathology revealed a nodular tumor with unclear boundaries, which was composed of heavily pigmented dendritic cells and more pigmented spindle cells.

OUTCOMES

There was no recurrence during 3 years follow-up.

CONCLUSION

Invasive cellular blue nevus of the spine can be wrongly diagnosed as spinal meningeal melanocytoma and meningeal melanoma due to its special cell behavior and rarity. Therefore, it is important to understand its pathological and clinical characteristics to avoid over-treatment.

Melanocytic naevi, melanocytomas and emerging concepts

With the elucidation of the genetics of melanocytic tumours, new concepts have emerged. An important one is the identification of 'intermediate' melanocytic tumours, those with genetic progression events beyond those of melanocytic naevi but that are not fully malignant. Thus, melanocytic tumours exist on a genetic spectrum that likely corresponds to biological behaviour. There are multiple pathways to melanoma development with different initiating events and characteristic benign melanocytic neoplasms and the precise placement of tumours on these pathways remains to be established and the corresponding risks of progression quantified. In this review, I discuss the classification of melanocytic naevi based on clinical, histopathological and genetic features, as well as the concept of melanocytomas with discussion of specific recognisable subtypes.

Cellular blue nevus tumor presenting as a submandibular lymph node in a 16-year-old

The cellular blue nevus tumor is a type of dendritic melanocytic nevus that is typically benign and exceedingly rare. The incidence of all blue nevi is about 1%, usually affecting the adult population and appearing on the extremities, sacrococcygeal or gluteal regions. There have only been a handful of case reports cited in the literature where cellular blue nevi present in the head and neck region, usually affecting the scalp and young adult population (7, 8). As such, it is exceedingly rare to encounter a cellular blue nevus tumor in the neck or infiltrating into neck lymph nodes. Here we report a rare case of a cellular blue nevus tumor presenting as a right neck mass in a pediatric 16-year-old patient, shown to invade into the submandibular lymph node and surrounding soft tissue. It is important to be aware of the cellular blue nevus tumor as a differential diagnosis in pediatric neck masses. Histological evaluation is necessary to determine tumor aggression and malignant potential which can guide further treatment in pediatric patients.

Uterine Cellular Blue Nevus Arising in Mullerian and Pelvic Dendritic Melanocytosis: Case Report of a Rare Phenomenon to Be Distinguished From Uterine Melanoma

A 37-yr-old woman presented to the gynecology clinic with abnormal uterine bleeding in the setting of known, large uterine fibroids. Preoperative endometrial biopsy identified atypical melanocytic cells concerning for uterine melanoma. Care was transferred to the gynecologic oncology service for hysterectomy. Intraoperative findings included macular, blue-black pigmentation of the peritoneum of the bladder and cervix, which was resected and sent for frozen section, confirming melanocytic neoplasia. The hysterectomy revealed multiple tan leiomyomas up to 12 cm, and a distinct 3 cm black, incompletely circumscribed mass in the endomyometrium composed of bland spindled cells with delicate melanin granules. The tumor cells were positive for Sox-10, BAP1, and Mart-1 (Melan-A) and negative for PRAME, PD-L1, and BRAFV600E by immunostains. Microscopic elements of similar melanocytes and melanophages were found in the cervix and bladder peritoneum. Molecular analysis of the uterine tumor identified a GNA11 mutation but no TERT or BAP1 mutation. The uterine melanocytic tumor has characteristic findings of a cellular blue nevus arising in association with dendritic melanocytosis of Mullerian and pelvic tissues, a rarely seen benign phenomenon that should be distinguished from malignant melanoma of the upper genital tract.

Melanocytic lesions with blue naevus-like (dendritic) morphology: an update with an emphasis on histopathological, immunophenotypic, and molecular features

An accurate diagnosis of melanocytic lesions requires a thorough histopathological evaluation accompanied by appropriate correlation with clinical examination findings. Although most melanocytic lesions can readily be classified as one of the defined diagnostic entities according to well-established diagnostic criteria, a subset of melanocytic lesions, particularly those with blue naevus-like (pigmented dendritic) morphology, have notoriously constituted an enduring challenge for pathologists. These lesions are rare and often show histological ambiguities, with features of both benignity and malignancy, thereby making accurate risk assessment and prediction of their biological behaviours difficult on histological grounds alone. Herein, we outline a practical and systematic approach for the diagnosis of melanocytic lesions with dendritic morphology, with a particular focus on histological and immunophenotypic features that help to distinguish one entity from another. In this review, we provide the most current knowledge on these melanocytic lesions in the literature and our experience with these rare entities, and we discuss the utility of molecular techniques as an ancillary tool, especially in histologically ambiguous and/or borderline lesions.

BAP-1 Expression Status by Immunohistochemistry in Cellular Blue Nevus and Blue Nevus-like Melanoma

The family of blue nevi includes the common blue nevus (BN), cellular blue nevus (CBN), and atypical BN, while melanomas with BN-like morphology can either arise in association with a blue nevus (MABN) or in the de novo setting mimicking cellular blue nevus (MMCBN). Recent molecular and immunohistochemical studies have demonstrated loss of BAP-1 in MABN/MMCBN but not in BN/CBN, suggesting that loss of BAP-1 correlates with a malignant phenotype in these lesions. In this study, we applied anti-BAP-1 antibodies to a series of CBN/BN (n = 11) and MABN/MMCBN (n = 4). Nuclear BAP-1 expression was detected in the majority of CBN/BN (n = 10/11) but was lost in 1 case. Most cases of MABN/MMCBN showed loss of nuclear BAP-1 expression (n = 3/4), with one case of MMCBN showing preserved BAP-1 expression. Demonstration of BAP-1 loss in a single case of CBN and preservation of BAP-1 expression in 1 case of MMCBN may indicate that detection of alterations in BAP-1 protein expression by immunohistochemistry may not be a completely reliable biomarker for the distinction of BN/CBN from MABN/MMCBN. Further investigation of the significance of BAP-1 loss/preservation in BN-like tumors is warranted.

Compound blue nevus: a reappraisal of the concept in the genomic era

We report a series of 21 compound blue nevi, a rare variant in the vast clinical and morphological spectrum of blue melanocytic proliferations. Clinically, they presented in young adults, with a slight female predominance. One-third were located on the dorsum of the foot. Morphologically, all cases displayed large dendritic melanocytes restricted to the deep layers of the epidermis. The compound component was central and evenly distributed. Melanocytic density ranged from scarce isolated cells to a confluent lentiginous architecture. In 12 of the 21 cases, junctional nests of small, bland, weakly pigmented melanocytes were associated. These nests became confluent in the most cellular cases. In all cases, a dermal component was immediately present underneath, mainly of cellular blue nevus-type. All cases were genetically confirmed to harbor either a GNAQ or GNA11 hotspot mutation. This study expands the morphological spectrum of blue nevi that should not be restricted to a strictly intradermal melanocytic proliferation.

The color of skin: black diseases of the skin, nails, and mucosa

Gradations in skin color are a consequence of differing amounts of melanin and their varying distribution. Although many darkly pigmented skin lesions are melanocytic and can be attributed to melanin content, the color of a black lesion can also be due to blood, necrotic tissue, or exogenous pigment. The source, pattern, and distribution of the color in black lesions usually offer important insight into its etiology. This contribution reviews conditions that can take on a black color, discussing the cause of the hue and any additional impact sun exposure may have.

Blue Nevi of the Ocular Surface: Clinical Characteristics, Pathologic Features, and Clinical Course

PURPOSE

Blue nevus is a melanocytic tumor that is commonly found in the skin. Extracutaneous presentations, including the ocular surface, are rare. As such, the purpose of this study was to characterize the clinical features and clinical course of congenital melanocytic tumor (blue nevus) of the conjunctiva.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

Twenty-one patients with 23 blue nevi of the ocular surface that were excised surgically between 2000 and 2016.

METHODS

Chart review of patients identified from a database search of the Florida Lions Ocular Pathology Laboratory records. Pathologic diagnoses were confirmed by 2 pathologists (S.R.D. and G.E.). All specimens were bleached and, tissue permitting, stained using SOX10 (MilliporeSigma, Darmstadt, Germany) and CD68 (Leica Biosystems, Nussloch, Germany).

MAIN OUTCOME MEASURES

Clinical characteristics, pathologic features, and clinical course.

RESULTS

Mean age of the population was 55±15 years; 71.4% (n = 15) were white and 57.1% (n = 12) were men. One patient had 3 lesions, for a total of 23 lesions examined. Clinically, 13 lesions were on the bulbar conjunctiva, 3 were on the tarsal conjunctiva, 3 were in the fornix, 2 were caruncular, 1 was episcleral, and 1 was at the limbus. Before excision, 8 patients were thought to have primary acquired melanosis, 4 with concern for primary conjunctival melanoma, and 1 thought to have metastatic disease from a plantar melanoma. Five lesions were thought to be benign, and in 8 patients, the lesions were identified incidentally after other ocular surgeries, with no diagnosis of the lesions before excision. Pathologic features were consistent with simple blue nevi in 21 lesions and cellular blue nevus in 2 lesions. No malignant transformations were noted in any patient over the mean 20.2-month follow-up period (range, 2 weeks-103 months).

CONCLUSIONS

Blue nevus is a rare deeply pigmented congenital melanocytic lesion with a benign clinical course that can appear clinically similar to primary acquired melanosis or melanoma.

Cyclin D1 and p16 Expression in Blue Nevi and Malignant Melanoma

BACKGROUND

Differentiating benign blue nevi from blue nevus-like melanoma can be diagnostically challenging. We aimed to determine the utility of immunohistochemical staining for p16 and cyclin D1 in distinguishing benign blue nevi and malignant melanoma.

MATERIALS AND METHODS

Thirty-two biopsy specimens taken between 2007 and 2015 were obtained from the Department of Pathology at the Queen's Medical Center in Honolulu, HI. These included 9 common blue nevi, 8 cellular blue nevi (2 with atypical features), and 15 malignant melanomas (3 blue nevus-like melanoma). The primary outcome was the difference in p16 and cyclin D1 staining between benign blue nevi and malignant melanoma. Staining of specimens for p16 and cyclin D1 was graded on the strength of staining, and the percent of tumor that stained positive. A specimen was deemed positive if it showed 2+ staining in ≥50% of the tumor.

RESULTS

The majority (82%) of blue nevi stained negative for p16. There was not a significant difference between p16 staining in benign blue nevi and melanoma (P=0.06). Eleven (73%) melanomas stained positive for cyclin D1 with a sensitivity of 0.73 and positive predictive value of 1.0. All blue nevi were negative for cyclin D1, making its specificity 1.0 and its negative predictive value 0.8. This difference in cyclin D1 staining in blue nevi and melanoma was significant (P=0.0001).

CONCLUSIONS

Cyclin D1 may be useful in differentiating benign blue nevi from melanoma.

Blue nevus-like and blue nevus-associated melanoma: a comprehensive review of the literature

BACKGROUND

Malignant blue nevus, blue nevus-associated melanoma and blue nevus-like melanoma are all terms used to describe malignant melanomas arising from, in association with, or resembling blue nevi. This review is aimed at summarizing the available literature to reduce the confusion surrounding this rare malignancy, and aid the surgeon in choosing further diagnostic or therapeutic measures.

METHODS

We conducted a search of Medline, Embase, Science Direct, Scopus and the Cochrane Library for all full text articles published in English that reported on a malignant melanoma arising from, in association with, or resembling a blue nevus.

RESULTS

We identified 91 cases that fit the criteria above. The mean age at diagnosis was 45 years, with a slight male predominance (males: 48; females: 43). Metastatic cases were reported in 55% (n = 50), of which 16 were metastatic at the time of diagnosis, 16 developed metastases within the first year and 18 within 5 years of initial diagnosis. The mean Breslow thickness was 6.8 mm at the time of diagnosis (n = 39).

CONCLUSIONS

The histological criteria for diagnosing this malignancy are very poorly defined, and may contribute to the substantial confusion surrounding the terminology. There is no consensus on which prognostic indicators predictive of outcome in 'conventional' malignant melanoma are applicable to blue nevus-like melanoma/blue nevus-associated melanoma. However, two larger case series have demonstrated a significant association between Breslow thickness (or largest tumour dimension when non-epidermal) and recurrence-free survival, as well as rate of local recurrence, but larger studies are needed to confirm this.

Metastatic Cellular Blue Nevus: A Rare Case With Metastasis Beyond Regional Nodes

In this study, we present a rare case of a 35-year-old man with a long-standing blue-black lesion on his left hand with subsequent infraclavicular and axillary lymph node tumor deposits. The hand lesion and lymph nodes were excised revealing histological, immunohistochemical, and molecular findings consistent with cellular blue nevus. Despite nonregional lymph node involvement, there has been no progression at 12-months follow-up. This is an index case of a cellular blue nevus with metastasis to both regional and nonregional lymph nodes. The lack of atypical/malignant features in this lesion makes the metastatic behavior extraordinary, and hence the prognosis of lesions of this type is indeterminate.

Perineural Pseudoinvasion: An Unusual Phenomenon in Nonmalignancies

Perineural invasion (PNI) is characterized as tumoral or nontumoral cells invading in or around the nerves. The neural invasion is considered as a histopathologic characteristic for malignancy and is considered a mechanism for its spread. Both of these patterns usually portend a poor prognosis and very often are markers to prompt additional treatment. There are also some nonmalignancies representing PNI, including benign neoplasms, mimicking lesions, and disorders, such as chronic pancreatitis and endometriosis. The previously recommended terms are PNI, spread, or infiltration. To distinguish PNI in malignancies from that in nonmalignancies, we propose the term "perineural pseudoinvasion" to convey their nonmalignant behavior. Despite the low prevalence, awareness of this benign pseudoinvasion is necessary to avoid aggressive treatment and its misdiagnosis with malignancies. We conducted a systematic search in PubMed and Scopus databases up to December 2015 to find articles reporting PNI in nonmalignancies. After screening, 63 articles were identified as relevant. There were also 2 review articles discussing PNI in nonmalignancies. We aim to present an overview of the perineural pseudoinvasion and to discuss the previously published review articles.

Dural Melanoma Associated with Ocular Melanosis and Multiple Blue Nevi

Background:

Primary meningeal melanomas of the central nervous system (CNS) are a rare malignant process with the majority originating from the leptomeninges. Primary dural melanomas have been reported to occur in isolation or in conjunction with Nevus of Ota. The association of primary dural melanoma with multiple cutaneous blue nevi has not been reported previously.

Objective:

To describe a case of a 41-year-old Asian woman patient with a primary dural melanoma that arose in association with ocular melanosis and multiple cutaneous blue nevi. The patient is alive almost more than 8 years after subtotal and subsequent total resection of her primary tumor. Primary dural melanomas, Nevus of Ota, and blue nevi are discussed in relation to their coexistence and potential for intracranial melanoma.

Conclusion:

CNS melanoma is regarded as an extremely aggressive disease with poor prognosis. This case and previous reports of dural melanomas occurring in isolation or with Nevus of Ota have demonstrated relatively prolonged survival after surgical intervention. We conclude that dural melanomas are less aggressive tumors requiring surgical extirpation only.

Cellular Blue Nevus Diagnosed following Excision of Melanoma: A Challenge in Diagnosis

A case of a 41-year-old woman with a history of nodular melanoma (NM), associated with an indurated dome-shaped blue-black nodule with a diameter of 1.2 cm in the gluteal region, is presented. Clinical diagnosis of the lesion, present from birth, was blue nevus. Recently, the nodule has been showing a mild enlargement and thus complete resection was performed. Histological analysis revealed a pigmented lesion with an expansive pattern of extension into the dermis and the subcutaneous adipose tissue. The lesion displayed an alveolar pattern as well as a pigmented dendritic cell pattern. The histology was consistent with cellular blue nevus (CBN); however, the history of NM which was excised one year earlier, as well as the clinical information about the slow growing lesion, included a differential diagnosis of CBN, borderline melanocytic tumor, and malignant blue nevus. Additional immunohistochemical (HMB-45, p16, and Ki-67) and molecular (BRAF V600E mutation) analyses were performed on both lesions: the CBN-like and the previously excised NM. Along with lesion history and histological analyses, p16 staining and BRAF were useful diagnostic tools for confirming the benign nature of CBN in this case.

Blue nevus and "malignant blue nevus:" A concise review

Blue nevi are a heterogeneous group of lesions that can display a variety of different clinicopathological characteristics. Although attempts are made to classify each lesion into defined subtypes, there can be overlap between the subtypes. The clinical and histolopathologic features of common blue nevi and cellular blue nevi are discussed, as well as blue nevi with atypical features and malignant lesions with features of blue nevi.

Genomic copy number analysis of a spectrum of blue nevi identifies recurrent aberrations of entire chromosomal arms in melanoma ex blue nevus

Blue nevi may display significant atypia or undergo malignant transformation. Morphologic diagnosis of this spectrum of lesions is notoriously difficult, and molecular tools are increasingly used to improve diagnostic accuracy. We studied copy number aberrations in a cohort of cellular blue nevi, atypical cellular blue nevi, and melanomas ex blue nevi using Affymetrix's OncoScan platform. Cases with sufficient DNA were analyzed for GNAQ, GNA11, and HRAS mutations. Copy number aberrations were detected in 0 of 5 (0%) cellular blue nevi, 3 of 12 (25%) atypical cellular blue nevi, and 6 of 9 (67%) melanomas ex blue nevi. None of the atypical cellular blue nevi displayed more than one aberration, whereas complex aberrations involving four or more regions were seen exclusively in melanomas ex blue nevi. Gains and losses of entire chromosomal arms were identified in four of five melanomas ex blue nevi with copy number aberrations. In particular, gains of 1q, 4p, 6p, and 8q, and losses of 1p and 4q were each found in at least two melanomas. Whole chromosome aberrations were also common, and represented the sole finding in one atypical cellular blue nevus. When seen in melanomas, however, whole chromosome aberrations were invariably accompanied by partial aberrations of other chromosomes. Three melanomas ex blue nevi harbored aberrations, which were absent or negligible in their precursor components, suggesting progression in tumor biology. Gene mutations involving GNAQ and GNA11 were each detected in two of eight melanomas ex blue nevi. In conclusion, copy number aberrations are more common and often complex in melanomas ex blue nevi compared with cellular and atypical cellular blue nevi. Identification of recurrent gains and losses of entire chromosomal arms in melanomas ex blue nevi suggests that development of new probes targeting these regions may improve detection and risk stratification of these lesions.

Congenital neurocristic tumor presenting as an isolated calvarial defect in an infant: case report

In infants, the presence of a cranial defect may be due to a variety of traumatic, inflammatory, neoplastic, and congenital abnormalities. Differentiation between these possible etiologies is facilitated by clinical presentation, patient history, and physical examination. Congenital cutaneous neural crest-derived lesions are unlikely to be considered in a patient presenting with an asymptomatic cranial defect without overlying mass or skin pigmentation. The authors present an unusual case of a 2-month-old infant with an asymptomatic calvarial defect with normal overlying skin. Pathology of the excised tissue showed features consistent with a congenital neurocristic tumor: a pigmented, neural crest-derived hamartomatous tumor that typically presents as a melanotic skin lesion.

Melanoma arising in association with blue nevus: a clinical and pathologic study of 24 cases and comprehensive review of the literature

Melanomas arising in association with blue nevi or mimicking cellular blue nevi comprise a relatively rare and heterogeneous group of melanomas. It remains controversial which prognostic indicators predictive of outcome in conventional cutaneous melanomas are applicable to this type of melanoma. Here, we describe the clinical and histopathologic features of 24 melanomas arising in association with blue nevi and correlate these with clinical outcome. The mean patient age was 49 years (range: 23-85) with a slight female predominance (15 females:9 males). The most common anatomic locations included the head and neck region (50%), the trunk (21%), and the buttock/sacrococcygeum (17%). Histologically, the tumors were typically situated in the mid to deep dermis with variable involvement of the subcutis, but uniformly lacked a prominent intraepithelial component. The mean tumor thickness (defined as either the standard Breslow thickness or, if not available due to the lack of orientation or lack of epidermis, the largest tumor dimension) was 20.9 mm (range: 0.6-130 mm). The mean mitotic figure count was 6.5/mm(2) (range: 1-30/mm(2)). Perineural invasion was common (38%). Follow-up was available for 21 cases (median 2.1 years). The median overall survival, recurrence-free survival, time to local recurrence, and time to distant recurrence were 5.2, 0.7, 2.6, and 1.6 years, respectively. Logistic regression analyses demonstrated a significant association between tumor thickness and recurrence-free survival (hazard ratio=1.02 per mm; P=0.04) and reduced time to distant metastasis (hazard ratio=1.03 per mm; P=0.02) with a similar trend toward reduced time to local recurrence (hazard ratio=1.02 per mm; P=0.07). No other parameters (age, anatomic location, mitotic figures, lymphovascular or perineural invasion, or type of associated blue nevus) emerged as significant. In addition, we provide a comprehensive review of 109 cases of melanoma blue nevus type described in the English literature and summarize our findings in this context.

The spectrum of grossly visible pigmented lesions in the uterine cervix: a prospective study

Pigmented lesions of the uterine cervix (UC) have not been systematically studied in the literature. Over an 18-mo period, we prospectively investigated the histologic spectrum of all macroscopically visible pigmented lesions of the UC. The incidence of pigmented UC was 1.6% (33/2118). Histologic examination revealed 32 cases (97%) with a histologic correlate, of which 26 lesions were of melanocytic nature including 25 blue nevi (BNs) (81%) and 1 melanotic macule (3%). The nonmelanocytic lesions included 1 case of focal granulomatous vasculitis (3%), 2 biopsy site-associated reactive changes with hemosiderin-laden macrophages (6.4%), 1 case of hemorrhagic Nabothian cyst (3%), 1 hemangioma (3%), and 1 case of multinucleated giant cell reaction to dark black carbon-like material (3%). Women with UC BN (1.2% incidence) were mostly whites (13/25, 52%) with a mean age of 47.4 yr (range, 31-64 yr). The number and size of BN per UC, all located in the endocervix, varied between 1 to 3 and 0.1 to 2 cm (mean, 0.68 cm). UC BN exhibited 3 distinct morphologic patterns: (1) stromal melanocytic focus composed of fine spindle cells (9/25, 36%); (2) mixed pattern with fine spindle, plump spindle, and epithelioid cells (15/25, 60%); and (3) nevoid stage with epithelioid cells (1/25, 4%). In contrast, cervical melanotic macule was located in the squamous epithelium of the ectocervix and characterized by hyperpigmentation of the basal keratinocytes admixed with scattered slightly enlarged melanocytes. In conclusion, pigmented lesions of the UC are not as uncommon as reported and mostly benign in nature. Several cases may require deeper levels for their detection and to exclude the rare phenomenon of UC melanoma.

Melanoma arising in a large plaque-type blue nevus with subcutaneous cellular nodules

Melanoma may arise in association with and/or simulate the appearance of a cellular blue nevus. The distinction of a cellular blue nevus with atypical features from blue nevus-like melanoma can be difficult. One rare setting, in which one may face this diagnostic challenge, is nodule formation in a large plaque-type blue nevus. We have previously reported 2 patients with cellular blue nevus-like subcutaneous nodules without overt malignant features and indolent clinical behavior. Herein we report a patient who developed malignant melanoma in association with a large plaque-type blue nevus. A 46-year-old woman with a history of "cellular blue nevus" of the breast that developed 7 years earlier during pregnancy had soft tissue nodules at the prior surgical site. She was found to have melanoma associated with a large plaque-type blue nevus, which involved the skin and subcutis of the chest wall and extended into breast parenchyma. Ten years after mastectomy and axillary node dissection with negative lymph nodes, the melanoma recurred as a subcutaneous chest wall nodule. Cytogenetic analysis revealed a number of aberrations, including deletion of 6q and gains of 6p and 8q. The patient then developed visceral metastases, first to the liver, and died of widely metastatic melanoma. In contrast, the cytogenetic findings of a previously reported cellular blue nevus-like nodule in a patient with a large plaque-type blue nevus were normal. That patient is still alive with no evidence of melanoma 16 years after the surgical excision of the subcutaneous cellular blue nevus-like nodule.

Oral atypical cellular blue nevus: an infiltrative melanocytic proliferation

The atypical cellular blue nevus is an extremely rare nevomelanocytic lesion which lacks precise histologic characterization in the current literature. Given the potential for significant architectural and cytologic overlap with melanoma, further study, including molecular analysis, is needed. This is the first description of an atypical cellular blue nevus of the oral cavity.

Acquired patch-type blue nevus with overlying vitiligo: a case report

BACKGROUND

Blue nevi are a group of congenital and acquired dermal melanocytoses characterized by a blue-gray appearance on the skin. The common blue nevus and cellular blue nevus are the most common subtypes. Patch-type blue nevus is rather rare.

OBSERVATIONS

We describe a 77-year-old Chinese male with a 6 × 8-cm non-palpable blue patch overlaid by a depigmented patch on the back of the left scalp. Histological examination of the blue-gray patch showed numerous spindled and elongated bipolar dendritic melanocytes in the upper reticular dermis and an absence of epidermal melanocytes. Immunohistochemically, these dendritic melanocytes were positive for S-100 and HMB-45. A diagnosis of a patch-type blue nevus with overlying vitiligo was made after the biopsy.

CONCLUSIONS

The patient presents an unusual manifestation of patch-type blue nevi with overlying vitiligo. To the best of our knowledge, these features have not been previously described.

Vaginal blue nevus: report of a case and review of the literature

OBJECTIVE

: Blue nevi are extremely rare in the vaginal canal and are suspicious for melanoma, especially when multiple lesions are present. We describe a woman with multiple blue nevi of the vagina.

DESIGN

: We describe 1 case of multiple blue nevi of the vagina.

RESULTS

: A 37-year-old woman, status after therapy for serous carcinoma of the ovary, presented with multiple blue to black macular lesions present throughout the vagina. Two of the lesions were examined by biopsy and demonstrated dendritic melanocytes. The patient has been closely followed, and the lesions remain unchanged.

CONCLUSIONS

: Multiple vaginal blue nevi are an important differential diagnostic consideration for melanoma of the vagina. These lesions, however, are benign and require only clinical follow-up. Excision is unnecessary.

Blue Nevi and Variants: An Update

Context.—Blue nevi are a subset of melanocytic proliferations containing cells reminiscent of the embryonal neural crest–derived dendritic melanocytic precursors. They are common specimens in a general pathology practice, but some of their rare variants may pose diagnostic difficulty. Recent molecular studies provide new insights into genetics of blue nevi.

Objective.—To critically review clinical and histologic features of blue nevi with emphasis on diagnostic problems and rare variants, as well as to provide an update on the pathogenesis of blue nevi.

Data Sources.—Published peer-reviewed literature and personal experience of the authors.

Conclusions.—Challenging areas in diagnosis of blue nevi include recognition of amelanotic, desmoplastic, atypical, and malignant variants of blue nevus. Recent data show that mutations in genes responsible for common nevi or melanomas such as BRAF, NRAS, or c-kit are rare in blue nevi. Benign and malignant blue nevi harbor frequent mutations in the Gαq class of G-protein α subunits, Gnaq and Gna11 proteins.

Cellular blue nevus of the uterus: a case report and review of the literature

Cellular blue nevus is extremely rare in the gynecologic tract with only 2 cases reported thus far, one in the myometrium and the other in the cervix/vagina/hymenal ring. In this report, we present the clinicopathologic features of the second case of cellular blue nevus arising in the myometrium. The patient was a 48-year-old woman who underwent a hysterectomy with bilateral salpingo-oophorectomy for uterine leiomyomas. On gross examination, the uterus showed a subserosal, 1.0×0.5×0.3 cm, dark red nodule in the anterior uterine wall in addition to multiple leiomyomas. Microscopically, the subserosal dark nodule had an irregular contour with only focal areas of pushing circumscribed border. The tumor cells were arranged either in sheets or confluent nests. The tumor cells were mostly epithelioid with clear cytoplasm, but in some areas the tumor cells were spindle-shaped with eosinophilic cytoplasm. Both types of cells contained intracytoplasmic melanin. The nuclei of the tumor cells were either oval, round, or elongated with no or minimal irregularities of the nuclear membrane, evenly distributed chromatin, inconspicuous nucleoli, and no obvious mitotic figures. Focally some of the epithelioid cells showed enlargement of the nucleus, irregularities in the nuclear contour, and rare nuclear pseudoinclusions. The tumor cells were positive for S-100, HMB-45 antigen (strong and diffuse pattern), and MART-1. Anti-Ki-67 showed a low proliferative activity (only a rare cell marked for this immunomarker). Thus, a diagnosis of cellular blue nevus was established. After a follow-up of 2 months, the patient had no evidence of the disease.

State of the art, nomenclature, and points of consensus and controversy concerning benign melanocytic lesions: outcome of an international workshop

The following communication summarizes the proceedings of a one-day International Workshop focusing on the histology of benign melanocytic nevi. Areas of controversy identified in 6 focus sessions were the nomenclature and relationships among common nevi including nevi with halo reactions, traumatized nevi, "dysplastic" nevi, and nevi from particular anatomic sites; developmental biology and frequency of malignant transformation associated with congenital nevi; the characterization and biologic nature of atypical spitzoid neoplasms; the basic definition of particular melanocytic cellular phenotypes, and the nomenclature and biologic nature of many candidate blue nevi, combined nevi, and other controversial lesions such as deep penetrating nevus and pigmented epithelioid melanocytoma. Concentrated data collection and follow-up, molecular characterization, and future consensus Workshops may facilitate the resolution of some of these problems. The Group recommended the description of ambiguous or "borderline" lesions as tumors with indeterminate or uncertain biologic/malignant potential. The participants also advised that such lesions at a minimum should be managed by complete excision with clear surgical margins.

Pigmented lesion pathology: what you should expect from your pathologist, and what your pathologist should expect from you

The first part of this review examines the reliability of histologic diagnosis in pigmented lesions, as measured by concordance studies and medicolegal analysis. It emphasizes the role of clinicians in maximizing that reliability, by providing adequate clinical descriptions, using appropriate biopsy technique, and critically interpreting pathology reports. It identifies those entities that are especially problematic, either because they cannot be reliably recognized by the histopathologist or because their histology is a poor guide to their biologic behavior. The second part of the review is a guide to some of the more difficult and controversial pigmented lesions, including dysplastic nevus, spitzoid nevi and melanomas, cellular blue nevus, animal-type melanoma, and deep penetrating nevus.

Blue nevi and related lesions: a review highlighting atypical and newly described variants, distinguishing features and diagnostic pitfalls

Blue nevi and related entities are a heterogenous group of congenital and acquired melanocytic tumors that includes established entities such as dendritic ("common") blue nevus and cellular blue nevus, and their numerous clinical and pathologic variants, such as deep penetrating nevus. They share several clinical and morphologic features including their blue tinctorial properties, the presence of a dermal proliferation of spindle, fusiform or ovoid cells, associated melanin pigment (both within the melanocytic tumor cells and also within macrophages) and stromal sclerosis and, at least focal positivity for HMB-45 (Gp100). Some variants, such as deep penetrating nevus, often show considerable variation in nuclear size and shape, and, as a consequence, are at risk of being misdiagnosed as melanoma by those unfamiliar with their characteristic morphologic features. The so-called malignant blue nevus is a controversial term denoting melanomas arising in association with or exhibiting some morphologic similarities to blue nevus. There are also lesions that are probably related to blue nevi, such as the recently described pigmented epithelioid melanocytoma and the neurocristic hamartomas, whose nature, biologic behavior, and relationship to the better established entities remains to be clearly established. This review aims to present a brief overview of these lesions, highlighting their pathologic characteristics, distinguishing features and potential diagnostic pitfalls, with particular emphasis on recently described entities, molecular findings, controversial areas, and approaches to diagnosis.

Sentinel lymph node biopsy in pediatric and adolescent cutaneous melanoma patients

BACKGROUND

The rarity of melanoma in young patients, particularly pediatric ones, has to date precluded any valid comparisons being made between young patients and adults undergoing sentinel lymph node biopsy (SLNB) for intermediate thickness localized melanoma. The present study takes advantage of the large Sydney Melanoma Unit (SMU) database to clarify this issue.

MATERIALS AND METHODS

Clinical and pathologic data on pediatric and adolescent AJCC Stage I and II cutaneous melanoma patients aged <20 years undergoing SLNB at the SMU between January 1993 and February 2008 were reviewed. SLNB positivity rates and outcomes in these patients were compared with adult SMU patients.

RESULTS

In 55 young patients, overall median tumor thickness was 1.7 mm (range, 0.6-5.2 mm) and overall SLNB positivity rate was 14 of 55 (25%), tumors tending to be thicker (median, 2.6 mm), and SLNB positivity rate higher (2 of 6; 33%) in patients aged <10 years. Of the 14 patients, 13 underwent immediate completion lymph node dissection (CLND); 2 patients had non-SLN metastases (15.4%). Only 0.7% of a total of 295 lymph nodes removed at CLND were involved with melanoma. In 14 SLNB-positive patients with follow-up data, 3 (21%) have died from melanoma after a median follow-up of 60 months, compared with 42% of 356 SLNB positive adults.

CONCLUSIONS

Although the SLNB positivity rate was higher in pediatric and adolescent melanoma patients than in adults (25% vs. 17%, respectively), non-SLN positivity and melanoma-specific death rates were low.

So-called "malignant blue nevus": a clinicopathologic study of 23 patients

BACKGROUND

Melanomas that arise in association with or that resemble blue nevi are extremely rare and have been termed "malignant blue nevi." The authors report on a single-institutional clinicopathologic study of "blue nevus-like melanomas" (BNLMs).

METHODS

Twenty-six patients were identified with a "malignant blue nevus" over 29 years at the Sydney Melanoma Unit. Twenty-three patients were included in the current study after pathologic review. Clinical outcomes of those patients were compared with the outcomes in a matched control group of patients with melanoma (matched for age, sex, Breslow thickness, Clark level, ulceration, and anatomic site).

RESULTS

The median patient age was 44 years, and men comprised 65% of the patients. The tumors were distributed evenly among skin sites, and their median Breslow thickness was 5.5 mm. After a median follow-up of 36.5 months, there was no difference in survival (P = .702) between patients with BNLM and patients in the control group.

CONCLUSIONS

BNLMs tended to present at a more advanced stage, with thicker primary tumors, but had a metastatic pattern comparable to and was not more aggressive in behavior than other types of melanoma. The authors concluded that BNLMs should be treated in the same way as any other melanoma variants based on clinical staging and pathologic prognostic indices.