Psammomatous malignant melanoma arising in an intradermal naevus

Rosette-like formations in melanocytic neoplasms: A case report and literature review

Homer-Wright-like rosettes are a common finding in neural tumors but seldom seen in melanocytic nevi and melanoma. We report a case of a 23-year-old male with a compound melanocytic nevus with such rosette-like structures and summarize the current literature on this histopathological feature in melanocytic neoplasms. A symmetric, well-circumscribed, compound nevus consisting of aggregations of epithelioid melanocytes with eccentric nuclei and central eosinophilic cytoplasm, resembling Homer-Wright rosettes, was present on biopsy. Immunohistochemical stains strongly supported a melanocytic entity and were negative for NTRK1/2/3, a fusion protein potentially associated with rosette-like structures. We found 17 other cases of benign melanocytic nevi, including 9 atypical Spitz tumors and 6 Spitz nevi, and 11 malignant melanomas, including 3 Spitz melanomas and 4 metastases. We observed remarkable diversity among lesion morphologies containing rosettes, as well as level of prominence and cytology of the rosettes themselves. This case illustrates the morphologic malleability of neural-crest-derived lesions to share microscopic and phenotypic attributes.

Nevus, melanoma or something else? Mesenchymal neoplasms with melanocytic differentiation

The overwhelming majority of cutaneous neoplasms with melanocytic differentiation are nevi, melanomas and more rarely melanocytomas. Nevertheless, there is also a group of mesenchymal neoplasms with genuine melanocytic differentiation which can create diagnostic difficulties with significant repercussions. These can rarely present as primary or metastatic cutaneous lesions. Theones that are relevant to a dermatopathologist include malignant melanotic nerve sheath tumor, perivascular epithelioid cell neoplasm and clear cell sarcoma. This work will provide a thorough review of clinical presentation, morphologic and immunohistochemical features as well as molecular pathogenesis of these tumors. We hope to familiarize the general dermatopathology readership with a group of neoplasms of mesenchymal lineage exhibiting melanocytic differentiation and ultimately avoid diagnostic misadventures. This article is protected by copyright. All rights reserved.

Melanotic Schwannoma of the Vulva: A Case Report and Review of the Literature

Melanotic schwannoma is a pigmented tumor of peripheral nerve differentiation. Primary cutaneous presentations are extremely rare, as the bulk of melanotic schwannomas tend to develop in paraspinal and axial sites. Tumors arise sporadically and in the setting of the Carney complex. Alterations in the gene encoding protein kinase A regulatory subunit-α (PRKAR1A) underlie most patients with the Carney complex and mediate melanotic schwannoma tumorigenesis. Melanotic schwannomas from noncutaneous sites can locally recur and metastasize widely, leading to a recent proposal to change the nomenclature to "malignant melanotic schwannian tumor." However, the clinicopathologic features of primary cutaneous melanotic schwannomas are relatively unexplored. We present a case of a nodule arising on the vulva of a 34-year-old woman. Microscopically, a dermal-based, heavily pigmented proliferation of plump spindled and epithelioid cells arrayed in nodules and fascicles was seen. Lesional cells stained positively for S100, Melan-A, and BAP1 but were negative for Prkar1α. Next-generation sequencing of a panel of 480 cancer-associated genes revealed that the tumor harbored a PRKAR1A p.S299fs truncating mutation and copy neutral loss of heterozygosity of chromosome 17q, the locus at which PRKAR1A resides. Importantly, no other genetic abnormalities or chromosomal copy number changes were identified. On the basis of combined histopathologic, immunohistochemical, and genetic features, a diagnosis of melanotic schwannoma was rendered. Overall, we present the first clinicopathologic description of a vulvar melanotic schwannoma, review the literature concerning cutaneous presentations of melanotic schwannoma, and propose that melanotic schwannian tumors native to skin may behave more indolently than their noncutaneous counterparts.

Psammomatous Melanotic Schwannoma: A Challenging Histological Diagnosis

Psammomatous melanotic schwannoma (PMS) is a rare pigmented tumor that can be part of the Carney complex. Here, we describe the case of a 35-year-old female patient presenting an isolated subcutaneous PMS. Histopathological analysis could not formally exclude the malignant nature of the tumor. The challenging histological diagnosis and consequently the management of the patient are described.

Rosette-like structures in the spectrum of spitzoid tumors

BACKGROUND

Spitz nevi demonstrate a diverse spectrum of morphologies. Recently, there have been two reported examples of Spitz nevi with rosette-like structures similar to Homer-Wright rosettes. Rosettes have also been described in melanomas and in a proliferative nodule arising in a congenital nevus.

METHODS

A retrospective review of 104 cases of Spitz nevi and variants (n = 51), pigmented spindle cell nevi (n = 26), combined melanocytic nevi with features of Spitz (n = 8), atypical Spitz tumor (AST, n = 9), and spitzoid melanoma (n = 10).

RESULTS

Rosette-like structures were present in 3 of the 104 cases (2.9%), including a compound Spitz nevus, a desmoplastic Spitz nevus, and an AST. All three cases demonstrated several foci of small nests of epithelioid cells with peripherally palisaded nuclei arranged around a central area of fibrillar eosinophilic cytoplasm. Immunohistochemical staining of the three spitzoid lesions demonstrated that the rosette-like structures express S100 protein, Melan-A, and neuron specific enolase (NSE) and lacked expression of neurofilament, glial fibrillary acidic protein and synaptophysin.

CONCLUSIONS

While uncommon, rosette-like structures can occur as a focal feature in Spitz nevi and AST. Rosette-like structures may represent a normal morphologic finding in Spitz nevi, and awareness of them may prevent misdiagnosis as a neural tumor or melanoma.

Improved discrimination of melanotic schwannoma from melanocytic lesions by combined morphological and GNAQ mutational analysis

The histological differential diagnosis between melanotic schwannoma, primary leptomeningeal melanocytic lesions and cellular blue nevus can be challenging. Correct diagnosis of melanotic schwannoma is important to select patients who need clinical evaluation for possible association with Carney complex. Recently, we described the presence of activating codon 209 mutations in the GNAQ gene in primary leptomeningeal melanocytic lesions. Identical codon 209 mutations have been described in blue nevi. The aims of the present study were to (1) perform a histological review of a series of lesions (initially) diagnosed as melanotic schwannoma and analyze them for GNAQ mutations, and (2) test the diagnostic value of GNAQ mutational analysis in the differential diagnosis with leptomeningeal melanocytic lesions. We retrieved 25 cases that were initially diagnosed as melanotic schwannoma. All cases were reviewed using established criteria and analyzed for GNAQ codon 209 mutations. After review, nine cases were classified as melanotic schwannoma. GNAQ mutations were absent in these nine cases. The remaining cases were reclassified as conventional schwannoma (n = 9), melanocytoma (n = 4), blue nevus (n = 1) and lesions that could not be classified with certainty as melanotic schwannoma or melanocytoma (n = 2). GNAQ codon 209 mutations were present in 3/4 melanocytomas and the blue nevus. Including results from our previous study in leptomeningeal melanocytic lesions, GNAQ mutations were highly specific (100%) for leptomeningeal melanocytic lesions compared to melanotic schwannoma (sensitivity 43%). We conclude that a detailed analysis of morphology combined with GNAQ mutational analysis can aid in the differential diagnosis of melanotic schwannoma with leptomeningeal melanocytic lesions.

Carcinoid-like pattern in melanoma: report of 4 cases

Cutaneous melanoma can produce a wide variety of unusual morphological appearances, sometimes mimicking other tumors. We report on 4 cases of melanoma with carcinoid-like features, namely, arrangement of neoplastic cells in trabecules, ribbons, pseudorosettes, rosettes, and/or small round islands. A total of 10 biopsies from 4 patients were available for a histopathological study comprising congenital nevus, a nodule that had developed in this nevus and its persistence/recurrence, 3 primary cutaneous lesions, 3 metastases, and a recurrent/persistent lesion. In 7 of these 10 lesions, the most characteristic finding was a distinctive arrangement of the neoplastic cells as trabecules, ribbons, pseudorosettes, rosettes, or small round insular islands, thus closely resembling cell arrangement in carcinoids of various organs. All these tumors were positive for melanocytic markers. No neuroendocrine differentiation was demonstrated immunohistochemically. We conclude that the carcinoid-like pattern in melanoma, namely, the pattern in which neoplastic cells are arranged in trabecules, ribbons, cords, rosettes, pseudorosettes, and small round insular nests resembling those in carcinoids, is a distinctive pattern, which may rarely occur in primary cutaneous melanoma, its recurrence or metastasis, or in a melanoma associated with a large congenital nevus. This morphological type of melanoma may produce a serious diagnostic pitfall, but despite a confusing microscopic appearance, these tumors seem to demonstrate a conventional immunohistochemical profile.

Psammomatous melanotic schwannoma presenting as colonic polyps

Psammomatous melanotic schwannoma is an uncommon neoplasm that usually occurs in the setting of Carney's complex. They can occur in the gastrointestinal tract with preferential location in the stomach. A 43-year-old female presented with two colonic polyps at routine endoscopy. The patient was asymptomatic and did not have features of Carney's complex. Both polyps were composed of melanin-containing epithelioid and spindle cells with several psammoma bodies. There was no evidence of cytological atypia or necrosis. The tumor was diffusely positive for S-100, and focally for HMB-45 and melan-A. The differential diagnosis includes melanoma, GIST, pigmented neuroendocrine tumor, and epithelioid leiomyoma. The lack of malignant features separates this lesion from melanoma while the immunophenotype of the other lesions is characteristic.

Fine-needle aspiration cytologic diagnosis of metastatic melanotic schwannoma: Familial case of a mother and daughter with Carney's complex and literature review

Carney's complex is an autosomal dominant, multisystem tumorous disorder that includes myxomas, spotty skin pigmentation, endocrine tumors, and peripheral nerve tumors. Psammomatous melanotic schwannomas have recently been included as a part of this complex. Here, we describe the first known familial case of a mother and daughter, both presenting with malignant, already metastatic, pigmented schwannomas initially diagnosed as metastatic melanoma by CT guided fine-needle aspiration. Patients with highly pigmented, extra-cutaneous lesions that are clinically and pathologically suspicious for metastatic malignant melanoma, without known primary tumor, should be evaluated for possible Carney's complex. Additional screening of family members should be recommended to exclude the presence of potentially malignant neoplasms, such as psammomatous melanotic schwannomas.

Primary intraosseous melanotic schwannoma of the fibula associated with the Carney complex

Described herein is a rare case of intraosseous melanotic schwannoma (MS) occurring in a long bone of a 13-year-old girl with a loss of heterozygosity (LOH) at 17q22-24, which contains the PRKAR1A gene encoding the protein kinase A regulatory subunit 1-a. Plain radiography and magnetic resonance imaging revealed a 10 cm expansile osteolytic lesion involving the proximal fibula. An excisional biopsy revealed a cellular tumor consisting of mildly pleomorphic spindle or oval to polygonal cells with frequent intranuclear pseudoinclusions, intracytoplasmic melanin pigments, nuclear palisades, Verocay body-like structures, and psammomatous calcifications. The tumor cells showed strong immunoreactivity for S-100 protein, HMB-45, and neuron-specific enolase. Ultrastructurally, the tumor cells were invested by continuous, multiplied external lamina and conspicuous melanosomes in various stages of maturation. These observations were compatible with psammomatous melanotic schwannoma (PMS). In addition, the detection of LOH for PRKAR1A strongly suggests that PMS in the present case is a manifestation of the Carney complex (CNC).

June 2004: a male in his late 60s with recurrent extracerebral tumor

June 2004: Over the past year, this man in late-60s had complained about progressive weakness of concentration and memory disturbances, associated with word finding difficulties. MRI examination revealed an extra-axial, parasagittal tumor 3 cm in diameter located in the left frontoparietal region. Five years ago, a meningioma in the same region, with radiographic appearance comparable to the present tumor had been totally removed. The histological picture of the current tumor was dominated by sheets of large rounded pleomorphic tumor cells with abundant eosinophilic cytoplasm and eccentric nuclei (rhabdoid cells). Cytoplasmic inclusions were frequent; occasionally,multinucleatedtumorcellswereseen. Mitoticfigures were absent and the MIB was 3%. Meningothelial lobules were scarce, and regions with fibroblastic appearance were absent. There were no psammoma bodies, necrosis or brain invasion. Moderate immunoreactivity for EMA was found. Additionally, strong cytoplasmic immunoreaction for vimentin within the rhabdoid cells was observed. Review of the previous material showed small islets of rhabdoid cells. Rhabdoid meningioma is an uncommon meningioma variant. It has been suggested that rhabdoid meningiomas are highly aggressive tumors (WHO grade III)and that the rhabdoid phenotype represents a marker of malignant transformation in meningiomas. Histologically, rhabdoid meningiomas usually exhibit signs of anaplasia, a high mitotic activity, and a markedly increased MIB-1 labeling index. Extracranial metastases may occur in the course of the disease. However, not all rhabdoid tumors appear to have anaplastic features (as this case illustrates). Another interesting feature of rhabdoid meningiomas is that in a significant number of cases, the rhabdoid cells appear only at the time of recurrence. Alternatively, as seen in this case, the rhabdoid cells may be already present in the primary meningioma, but not as the predominating histological feature.

Cutaneous psammomatous melanotic schwannoma: non-recurrence with surgical excision

BACKGROUND

Melanotic schwannoma is a pigmented nerve tumor that may be located in the skin and express local aggressivity. This tumor may occur singly. It may also be part of the Carney complex which consists of various, but specific, tumors.

OBJECTIVE

We report two cases of subcutaneous melanotic schwannoma localized on the trunk in two men aged 37 and 45 years.

METHODS

Conventional histology and immunohistochemistry were performed.

RESULTS

One melanotic schwannoma was associated with a cutaneous atypical myxoma and multiple melanocytic lesions, all being part of the Carney complex. The other case had no associated signs. In both cases, the melanotic schwannoma was completely excised and did not recur.

CONCLUSION

Melanotic schwannoma is rare and curable by surgery. It must not be confused with malignant melanoma and other pigmented neoplasms. The Carney complex should be carefully ruled out.

Cytomorphologic features of fine-needle aspiration of metastatic and recurrent melanoma

Melanoma is an aggressive malignancy with a growing prevalence. Although early detection and excision offer a potential cure, recurrences and metastases are not uncommon. Fine-needle aspiration (FNA) can play a vital role in their detection as a relatively noninvasive, rapid, and economical alternative for tracking disease evolution. Prior clinical history and classic cytological features of melanoma (loosely cohesive smear pattern and single cells with large nuclei, prominent nucleoli, and melanin pigment) aid in cytological diagnoses. However, not all melanomas contain melanin pigment or characteristic cytologic features. We examined a large series of melanoma cases to determine the incidence of melanin pigment, the most common cell morphology, and the presence or absence of apoptosis/necrosis associated with this highly aggressive neoplasm.