Cellular blue nevus ("melanocytoma") of the spinal meninges: electron microscopic and immunohistochemical features

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.

How Should We Treat Meningeal Melanocytoma? A Retrospective Analysis of Potential Treatment Strategies

BACKGROUND

Meningeal melanocytomas (MM) are rare primary melanocytic tumors of the leptomeninges with an incidence of 1:10,000,000. Until now, there has been only sparse information about this tumor entity. Here, we provide a meta-analysis of all cases published in the English language since 1972.

METHODS

A literature review was performed using PubMed and Web of Science. All published cases were evaluated for location, sex, age, therapeutic approach, and outcome. In total, we included 201 patient cases in our meta-analysis.

RESULTS

The majority of MM was diagnosed more frequently in men between the third and fifth decade of life. Surgery is the preferred therapeutic approach, and total resection is associated with the best outcome. Patients with partial resection or tumor recurrence benefit from adjuvant radiotherapy, whereas chemo- or immunotherapies do not improve the disease course. Malignant transformation was described in 18 patients. Of these, 11 patients developed metastasis.

CONCLUSIONS

We present the first retrospective meta-analysis of all MM cases published in the English language, including an evaluation of different treatment strategies allowing us to suggest a novel treatment guideline highlighting the importance of total resection for recurrence-free survival and characterizing those cases which benefit from adjuvant radiotherapy.

8-Year Follow-up for Woman with Spinal Meningeal Melanocytoma in S1 Nerve Root: Case Report and Literature Review

BACKGROUND

Primary melanocytic neoplasms in the central nervous system are rare lesions arising from leptomeningeal melanocytes. These lesions produce neural deficits that resemble those of a meningioma or a schwannoma radiologically.

CASE DESCRIPTION

A tumor around the left S1 root with an extension into the left paraspinal compartment was identified in a 32-year-old female with persistent left leg pain for 6 months. The tumor was hyperintense on T1-weighted image and hypointense on T2-weighted image with a homogeneous enhancement. The clinical features, radiologic presentations, treatment choice, and pathologic characteristic were illustrated. The treatment outcome was compared with those reported in the previous literature. The tumor was en-bloc resected with the S1 nerve root reserved. Grossly, the tumor was a soft, capsulated, well-circumscribed, black pigmented lesion. Immunohistochemistry revealed that the tumor cells were positive for HMB-45, S-100 protein, and vimentin. The patient's symptoms were greatly relieved postoperatively. No signs of local recurrence were observed.

CONCLUSIONS

Spinal meningeal melanocytoma inside the nerve root is rare and benign. It is difficult to diagnose and often misdiagnosed as schwannoma or meningioma. HMB-45 has been suggested as a significant marker for the diagnosis of meningeal melanocytoma. Complete surgical resection is recommended as the primary treatment. Radiotherapy, chemotherapy, and other treatments can be selected as adjuvant therapies, but their effects are controversial. The recurrence and metastasis rates also remain unclear.

Primary intramedullary melanocytoma in the cervical spinal cord: Case report and literature review

A 63-year-old man with right hemiparesis was found (on MRI) to have an expansive intramedullary tumorous lesion at the C2-C3 level. After complete neurosurgical tumor resection, the tumor was histologically categorized as an intermediate grade of intramedullary melanocytoma, an uncommon neoplasm. Based on this peculiar case and review of the literature, radical surgical resection appears to be the therapy of choice for intramedullary melanocytomas. However, their high recurrence rate and aggressive behavior suggest the need for close followup with serial MRI.

Spinal meningeal melanocytoma in the S-1 nerve root sheath with paraspinal extension mimicking schwannoma

BACKGROUND

Spinal melanocytomas are variants that can be extradural or intradural and are most often located in the intradural extramedullary compartment of the main thecal sac as in schwannomas. However, origin of this variant from the pure peripheral compartment of rootlets is exceedingly rare.

CASE DESCRIPTION

The authors present a case of spinal melanocytoma with confusing pathologic and radiologic features. This patient presented clinically with severe radiating pain on the right lower extremity. Before surgery, clinical and radiologic findings were consistent with a schwannoma. However, on operation, a coal-black pigmented lesion mimicking old blood clot was found inside the right S-1 root sheath, attached to the dura. The mass was completely removed and consequently the patient's symptoms improved.

CONCLUSIONS

The spinal melanocytoma should be included as a differential diagnosis before giving a presumptive diagnosis of schwannoma or hemorrhage for the patient with a space-occupying lesion at a peripheral rootlet. Intraoperative gross morphology and histopathologic findings facilitate differential diagnosis.

A 6-year-old girl with an extra-axial mass in the middle cranial fossa

A 6-year-old Japanese girl presented with psychomotor seizures. Magnetic resonance (MR) images disclosed a mass lesion in the left middle cranial fossa with an internal irregular-shaped area, which was hyperintense on T1-weighted images and hypointense on T2-weighted images. Gross total resection of the tumor was performed through left occipital craniotomy. The tumor was white-to-grayish hard tissue, focally showing blackish pigmentation. Histological, immunohistochemical and electron-microscopical analyses revealed that white-to-grayish hard tissue corresponded to an atypical meningioma, and the blackish pigmentation of the tumor was composed of non-neoplastic, reactive hyperplasia and colonization of meningeal melanocytes in the meningioma tissue. A meningioma with reactive hyperplasia and colonization of meningeal melanocytes is unusual, but it is clinically important to differentiate this entity from other melanocytic tumors.

Meningeal melanocytoma: clinical features and review of the literature

A case of meningeal melanocytoma in the posterior fossa of a 16-year-old male is reported. Computed tomographic and magnetic resonance imaging features are presented. Pathological investigation including light and electron microscopy, and immunohistochemical staining are discussed. Current literature is reviewed and differentiating criteria from meningioma and other pigmented tumours of the nervous system are discussed.

Melanocytoma in the orbital apex

We report a case of a 49-year-old man presenting with a melanocytoma located in the orbital apex. The tumor was subtotally removed and adjuvant chemotherapy was given. The patient has remained under follow-up for the past 12 years without any evidence of recurrence. Although the characteristic neuroradiological images of the lesion prove the presence of melanin, histological examination is crucial to establish the diagnosis of melanocytoma. Besides the clinical and neuroradiological presentation, the histological, immunohistochemical, and ultrastructural findings are described. To our knowledge, this is the second published case of intraorbital melanocytoma initially confined to the orbital apex. Melanocytoma should be included in the differential diagnosis of intraorbital tumors in such a location.

Melanocytic nevi simulant of melanoma with medicolegal relevance

A group of melanocytic benign nevi are prone to be misdiagnosed as nodular or superficial spreading melanoma. This review illustrates the most frequent forms of these nevi in direct comparison with their malignant morphologic counterparts. The nevi are: hyper-cellular form of common nevus to be distinguished from nevoid melanoma, Spitz nevus (vs spitzoid melanoma), Reed nevus (vs melanoma with features of Reed nevus), cellular atypical blue nevus (vs melanoma on blue nevus), acral nevus (vs acral melanoma), Clark dysplastic nevus (vs superficial spreading melanoma), desmoplastic nevi (vs desmoplastic melanoma), benign proliferative nodules in congenital nevi (vs melanoma on congenital nevi), epithelioid blue nevus (vs animal type melanoma) and regressed nevus (vs regressed melanoma). For each single 'pair' of morphological look-alikes, a specific set of morphological, immunohistochemical and genetic criteria is provided.

Unusual variants of malignant melanoma

A potential diagnostic pitfall in the histologic assessment of melanoma is the inability to recognize unusual melanoma variants. Of these, the more treacherous examples include the desmoplastic melanoma, the nevoid melanoma, the so-called 'minimal-deviation melanoma,' melanoma with prominent pigment synthesis or 'animal-type melanoma,' and the malignant blue nevus. Also problematic are the unusual phenotypic profiles seen in vertical growth phase melanomas; these include those tumors whose morphological peculiarities mimic cancers of nonmelanocytic lineage and those melanomas that express aberrant antigenic profiles not commonly associated with a melanocytic histogenesis. Metaplastic change in melanoma, balloon cell melanoma, signet-ring cell melanoma, myxoid melanoma, small cell melanoma and rhabdoid melanoma all have the potential to mimic metastatic and primary neoplasms of different lineage derivations. Abnormal immunohistochemical expression of CD 34, cytokeratins, epithelial membrane antigen, and smooth muscle markers as well as the deficient expression of S100 protein and melanocyte lineage-specific markers such as GP100 protein (ie HMB-45 antibody) and A103 (ie Melan-A) also present confusing diagnostic challenges. In this review, we will discuss in some detail certain of these novel clinicopathologic types of melanoma, as well as the abnormal phenotypic expressions seen in vertical growth phase melanoma.

Spinal meningeal melanocytoma. Report of two cases and review of the literature

The authors report on two patients with spinal meningeal melanocytoma and review the literature on this lesion. One case is particularly interesting because of the lesion's thoracic intramedullary localization. Meningeal melanocytoma is a benign but locally aggressive lesion and is very rarely associated with spinal localizations. This patient presented with paraparesis. Clinical and radiological examinations suggested the possibility of an intramedullary solid tumor. Thoracic laminectomy, posterior myelotomy, and tumor resection were performed; the mass was totally removed. The patient suffered no additional neurological deficit. During a 3-year follow-up period in which radiotherapy was not performed, the lesion did not recur. Total excision of the tumor is the best therapeutic option.

Therapy of meningeal melanocytomas

BACKGROUND

Meningeal melanocytomas are rare, benign central nervous system lesions with a high probability of recurrence. To the authors' knowledge, approximately 100 cases have been reported since 1972, when the entity first was described. In the current study, four therapies were compared with regard to local control and survival to identify which is best.

METHODS

All reported cases were reviewed with regard to extent of resection, radiotherapy, local control, and survival. If published data were incomplete, the authors were contacted for additional data. Patients were categorized by therapy: complete resection (CTR), complete resection followed by radiotherapy (CTR-RT), incomplete resection (ITR), and incomplete resection followed by radiotherapy (ITR-RT). Local control and survival were calculated using the Kaplan-Meier method. A multivariate analysis was performed including age, gender, tumor location, confirmation of extent of resection, and treatment schedule.

RESULTS

A total of 89 patients were included: 46 with CTR, 3 with CTR-RT, 23 with ITR, and 17 with ITR-RT. The 5-year local control rate was 80% after CTR, 100% after CTR-RT, and 72% after ITR-RT versus 18% after ITR (P < 0.001). The 5-year survival rate was 100% after CTR, CTR-RT, and ITR-RT, respectively, versus 46% after ITR (P < 0.001). Multivariate analysis demonstrated that therapy was the only variable that affected local control and survival significantly. In 14 patients treated with ITR-RT, RT was restricted to the tumor region. The radiation dose was 30-40 grays (Gy) in 6 patients, 45-55 Gy in 7 patients, and unknown in 1 patient. The 5-year local control rate was 86% after a dose of 45-55 Gy versus 27% after a dose of 30-40 Gy (P = 0.1).

CONCLUSIONS

CTR was found to be significantly superior to ITR with regard to both local control and survival. Outcome was significantly improved by RT after ITR. Doses of 45-55 Gy appeared to be more beneficial than doses of < or = 40 Gy.

Meningeal melanocytoma: an aggressive course for a benign tumor

A 79-year-old female presented with difficulty ambulating and was found to have weakness and hyperreflexia in the lower extremities. Magnetic resonance imaging (MRI) revealed a large T8-T9 intraspinal tumor. She underwent a thoracic laminectomy, and excision of an intradural extramedullary lesion. The surgical specimen was soft, black tissue that consisted of a moderately cellular, deeply pigmented tumor. The neoplastic cells proved to be melanocytic, and were devoid of overt features of anaplasia, i.e., prominent nuclear pleomorphism, necrosis, significant mitotic activity, and high proliferation indices. Four months postoperatively, MRI demonstrated focal areas of enhancement in the conus medullaris and in the fourth ventricle, indicating leptomeningeal spread. Subsequently, the patient underwent whole brain radiation. On repeat imaging, there was nodular enhancement of the fourth ventricle and throughout the spinal cord. Despite chemotherapy and radiation therapy, the disease advanced and the patient expired. Meningeal melanocytoma is a rare, histologically benign tumor with good prognosis. However, local aggressive behavior has been recorded, especially in cases of subtotal gross resection. On a literature review, there was one case of cranial posterior fossa meningeal melanocytoma with associated lesions in both suprarenal glands and the left kidney, but there were no cases with distant metastasis. In this report, we present an unusual case of spinal meningeal melanocytoma with diffuse spread throughout the craniospinal axis that proved to be fatal.

Lumbar spinal meningeal melanocytoma of the l3 nerve root with paraspinal extension: a case report

STUDY DESIGN

A case report of spinal meningeal melanocytoma with a dumbbell-shaped extension and its magnetic resonance imaging features is presented.

OBJECTIVE

To present a rare spinal tumor with pathologic and radiologic features.

SUMMARY OF BACKGROUND DATA

Meningeal melanocytomas are rare lesions usually found in the posterior fossa and upper cervical spine. The review of literature shows the variation in different studies. The characteristic magnetic resonance imaging features of meningeal melanocytoma have not yet been defined.

METHODS

A 33-year-old woman presented with a 3-year history of backache and weakness of her left lower limb. Magnetic resonance imaging showed a large dumbbell tumor at L3-L4 with extension in the paraspinal region. Schwannoma was the first possibility suggested by the MRI features. Histopathology of the lesion showed a meningeal melanocytoma.

RESULTS

The patient showed a significant recovery after surgery and a full course of radiotherapy.

CONCLUSIONS

Radiologic presentation could be confusing in cases of spinal dumbbell-shaped tumors. Awareness of the lesion characteristics will facilitate diagnosis and treatment of this condition.

Meningeal melanocytoma of the brain and oculodermal melanocytosis (nevus of Ota): case report and literature review

BACKGROUND

Meningeal melanocytomas are rare benign pigmented tumors of meningeal melanocytes. Nevus of Ota is a melanocytic pigmentation of the sclera and the skin adjacent to the eye. We report a rare case of parietal convexity meningeal melanocytoma associated with ipsilateral mucocutaneous melanosis and review the literature.

METHODS

A 17-year-old man presented with headache and blindness. There was left scalp and facial mucocutaneous melanosis. During surgery, speckled hyperpigmentation was seen in all layers of the scalp, bone, dura, and even ependyma. Pathologic examination of the tumor and scalp consisted of light microscopy and immunohistochemistry. In a literature review, the demographics (age, sex), clinical characteristics (site of lesion, duration of symptoms), therapeutic options (surgical excision, radiotherapy), and prognosis (recurrence, death, death related to the disease, and follow-up) were analyzed. For statistical analysis we used the independent sample t-test and chi(2) tests.

RESULTS

Ninety-five cases (45 intracranial and 50 spinal) of meningeal melanocytoma have been reported. The median age of patients with intracranial lesions (40 years) was significantly lower than that of patients with spinal lesions (49 years) (p = 0.016). Of the 95 patients, 57.9% were female. In the nervous system, melanocytes are more common in the infratentorial and cervical areas, but more than half of the tumors have been located in the supratentorial region and the thoracic spine. In 46 months median follow-up, tumor recurrence rate and tumor related death rate were 26.3% and 10.5%, respectively. These were not statistically significant for different therapeutic modalities. There was a trend toward shorter survival for patients who underwent subtotal tumor resection without radiotherapy compared with other groups.

CONCLUSION

The prognostic criteria, differential diagnosis, and the embryological aspects of meningeal melanocytoma are discussed with a review of the related literature.

Two cases of spinal meningeal melanocytoma

Meningeal melanocytoma is a rare pigmented tumor originating from the melanocytes that generally occurs in the posterior fossa and the spinal cord. Although it is known as a relatively benign tumor, some recurrences have been reported. We report two cases of spinal meningeal melanocytoma with immunohistochemical and ultrastructural studies. In addition, we include a summary of published cases since the first case of Limas and Tio in 1972.

[Spinal meningeal melanocytoma simulating neurinoma: case report]

Meningeal melanocytomas are infrequent tumors that when located in the spinal cord and because of their close relationship to the nerve root can resemble a neurinoma. The MRl can help to differentiate them from the neurinomas preoperatively. The case of a female patient harboring a cervical meningeal melanocytoma involving the C7 nerve root, and diagnosed preoperatively as an hourglass neurinoma is presented.

Suprasellar melanocytoma: a case of primary radiotherapy and review of the literature

Meningeal melanocytoma is a rare benign neoplasm of the central nervous system. Approximately 50% of the tumors are located intracranially with a preference for posterior fossa. We report a new case of intracranial suprasellar melanocytoma in a 57-year-old male patient treated with primary high-dose conformal radiotherapy to 50.4 Gy. Fourty-two months subsequent to treatment the tumor is well under control without neither deterioration of clinical symptoms nor progression of gross tumor volume on MR imaging. No late sequelae of treatment have been observed. A review of the literature is presented indicating that resection of melanocytoma is the treatment of first choice hampered by a relapse rate of approximately 30% depending on resection status. The role of adjuvant radiotherapy in patiens with complete resection of melanocytoma has not yet been defined. These patients carry a risk of relapse of approximately 15%, and adjuvant irradiation is currently not recommended. Primary high-dose radiotherapy has been shown to be effective in long-term control of the neoplasm in patients where no resection of the tumor could be accomplished. In case of incomplete resection of melanocytoma, data of the literature indicate that adjuvant radiotherapy may in fact increase long-term local control of the tumor. Requirements for optimal treatment results of radiotherapy are sufficiently high doses of, at least, 50 Gy for intracranial lesions and three-dimensional treatment planning guaranting precise targeting of the tumor volume with only a low-risk of late sequalae to the surrounding tissues.

Intracranial meningeal melanocytoma associated with ipsilateral nevus of Ota. Case report

In this report, the authors review the case of a man with a neurocutaneous syndrome. He presented with an intracerebral melanocytoma associated with a blue nevus of the scalp; its location and its appearance during childhood supported the diagnosis of a nevus of Ota. Meningeal melanocytomas are increasingly being diagnosed, but remain rare. Primary meningeal malignant melanoma is the first differential diagnosis to eliminate. Despite their common embryonic origin. the association of a melanocytoma with a nevus of Ota is rare. A nevus of Ota exhibits the same melanocytic proliferation and affects the trigeminal nerve territory. An ocular effect is not always observed. In contrast to an ocular lesion, a nevus of Ota rarely transforms into a malignant melanoma. It is found only among caucasians. During 4 years of follow-up review after surgery, the patient remained asymptomatic. Other than antiepileptic therapy, he received no complementary treatment and cerebral imaging revealed no evidence of recurrence.

Therapeutic options for meningeal melanocytoma. Case report

Meningeal melanocytomas are uncommon lesions. They are generally considered to be benign tumors that derive from leptomeningeal melanocytes. A rare case of a metastatic spinal meningeal melanocytoma is presented. All relevant cases reported in literature since 1972, when the term "meningeal melanocytoma" was first used, were reviewed. Rates of tumor recurrence from 1 to 5 years were calculated for this rare lesion, based on published data and on additional information obtained from personal contact with most of the authors. Recurrency rates of 47 patients suitable for evaluation were correlated with the different therapeutic approaches. Complete tumor resection alone and incomplete resection alone followed by irradiation appeared to be superior to incomplete resection alone in terms of disease-free survival. Statistical significance was achieved for complete tumor resection at follow up between I and 4 years (range p = 0.010-0.050) and for incomplete resection combined with radiotherapy after 2 years (p = 0.034). Complete tumor resection should be considered the best therapeutic option, followed by incomplete resection combined with postoperative radiotherapy.

Esophageal blue nevus: An isolated endoscopic finding

BACKGROUND

The occurrence of blue nevus has seldom been reported in extracutaneous sites and with no record in the esophagus.

CASE REPORT

A blue nevus was reported in the esophagus of a 58-year-old Chinese woman. On endoscopic examination, the lesion presented as linear patches of bluish pigmentation in the esophagus. The patient was free of symptoms 3 years after the endoscopic examination.

CONCLUSIONS

We believe this represents the first reported case of blue nevus in the esophagus. The clinicopathologic features, differential diagnoses, and the nature of the lesion are discussed, along with a review of the literature.

The relationship between melanocytes and peripheral nerve sheath cells (Part II): blue nevus with peripheral nerve sheath differentiation

Peripheral nerve sheath differentiation was studied in 120 specimens of blue nevi (112 specimens of "common" blue nevi and 8 specimens of "cellular" blue nevi). In 10 of 112 common blue nevi, fascicles of pigmented dendritic melanocytes or less pigmented spindle-shaped melanocytes with S-shaped nuclei were associated with wavy delicate collagen bundles. In 4 of these 10 specimens, the melanocytes showed a perifollicular arrangement. These nerve fascicle-like structures were seen in some cellular blue nevi (5 of 8 specimens). Structures closely resembling authentic nerve fascicles were not observed in common or cellular blue nevi. The fascicles with S-shaped nuclei and fibrillary collagenous tissue observed in blue nevi (which were well detected in the cellular type but rarely found in the common type) may be peripheral nerve sheath features and perhaps evidence that dermal dendritic melanocytes in the reticular dermis may have arisen within a peripheral nerve sheath milieu from primitive fibroblast-like precursors. Some of the examples presented here may be identical to those reported for "pilar neurocristic hamartoma" or "neurocristic hamartoma." I also speculate on the pathogenesis of blue nevi based on the observations made in this study.

Primary melanocytic neoplasms of the central nervous systems

Primary melanocytic neoplasms of the central nervous system (CNS) consist of a spectrum ranging from well-differentiated melanocytoma to its overtly malignant counterpart, melanoma. Diagnostically difficult intermediate lesions lie between these extremes. Clinicopathologic features of 33 cases were studied to define histologic appearances, diagnostic criteria, and the clinical behavior of lesions along this spectrum. Seventeen cases were well-differentiated, solitary leptomeningeal tumors classified as melanocytomas. They contained variably pigmented melanocytic cells arranged in tight nests, sheets, or fascicles. Mitotic rates ranged from zero to one per 10 high-power fields (HPFs), with most having zero per 10 HPFs. All tumors were immunoreactive for HMB-45 and S-100 protein and negative for epithelial membrane antigen. MIB-1 staining was low (<1-2%). Nuclei were regular, often with small, eosinophilic nucleoli. These lesions arose predominantly in the spinal canal (65%) in patients ranging in age from 17 to 73 years. None recurred after surgical resection. In contrast to these benign lesions, there were 13 cases with histologic and cytologic features consistent with those of malignant melanoma. These cases contained larger, cytologically atypical, pigmented tumor cells growing in loose nests or sheets, often with CNS invasion or necrosis. Some contained bizarre, pleomorphic nuclei; others were densely cellular and mitotically active, but less pleomorphic. Mitotic rates (mean, 5.7 per 10 HPFs) and MIB-1 labeling indices (mean, 8.1%) were higher than those of melanocytomas. Melanomas occurred at spinal (38%), posterior fossa (38%), and supratentorial (23%) levels in patients ranging in age from 15 to 71 years. After resection, 8 of 13 lesions recurred, with four being fatal (mean survival, 14 months). Of five totally resected melanomas, four did not recur (mean follow-up, 26 months). Three intermediate-grade melanocytic tumors could not be classified as melanocytoma or melanoma. All showed sheetlike growth patterns, microscopic CNS invasion, and occasional mitoses. MIB-1 staining ranged from 1% to 4%. One tumor recurred after 17 months; one patient was lost to follow-up after 5 months; and the third died after surgery. Although melanocytic tumors represent a spectrum of lesions, certain histopathologic features are helpful in predicting biologic behavior.

Meningeal melanocytoma: a case report and literature review

The clinicopathologic, immunocytochemical, and electron microscopic features of a case of meningeal melanocytoma arising in the phylum terminale are reported. Meningeal melanocytoma is an uncommon tumor that must be distinguished from metastatic or primary malignant melanoma, meningeal melanocytic nevi, pigmented meningioma, pigmented schwannoma or neurofibroma, and pigmented primitive neuroectodermal tumor. This is a difficult differential diagnosis that can be best archived by complementing histological examination with a selected panel of antibodies and, most important, electron microscopic study. The distinctive ultrastructural appearance of most of these lesions point to this technique as the gold standard in pigmented proliferations of the nervous system.

Primary intramedullary spinal melanoma: diagnostic and treatment problems

A 76-year old female patient with 9 year history of right mastectomy for an infiltrating ductal breast cancer and no evidence of recurrent nor metastatic disease, was admitted due to pain in the lower thoracic area radiating bilaterally to the posterior aspect of the chest wall at the same level, difficulties in micturition, urinary hesitancy, and progressive weakness of the lower limbs. Primary intramedullary spinal tumor was demonstrated by a MRI study of the spine, partially resected, and found to be a malignant melanoma on pathological study. Postoperative irradiation and administration of dexamethasone did not improve the neurologic status.

Melanocytoma of the foramen magnum

This report concerns a 66-year-old man with a melanocytoma arising at the foramen magnum. Magnetic resonance imaging disclosed a well-circumscribed tumor extending from the medulla oblongata to C1 with gadolinium enhancement. A heavily pigmented tumor located under the leptomeninges was removed surgically. Although the patient died 8 months later of renal cell carcinoma, no recurrence or metastasis of the melanocytoma was detected by radiographic examination. Microscopically, the resected tumor was composed of polygonal to spindle-shaped cells containing large amounts of melanin. The bland nuclei of the tumor cells were of uniform size. No mitotic figures were seen. The tumor cells were positively immunostained for S-100 protein and by antibody HMB-45. They were not stained using the Ki-67 (MIB-1) antibody, indicating low proliferative activity. The ultrastructural examination revealed numerous mature melanosomes and basal laminae surrounding nests of cells. The tumor was diagnosed as a melanocytoma on the bases of its microscopic features and the lack of Ki-67 immunoreactivity. The ultrastructural and immunohistochemical features of melanocytomas are distinct from those of meningiomas. It is likely that melanocytomas and melanotic schwannomas represent opposite extremes of the continuous spectrum of neuroectodermal tumors derived from the neural crest.

Psammomatous melanotic schwannoma of a spinal nerve root. Relationship with the Carney complex

A 36-year-old man had an oval, black, extradural tumor partly removed from the left C4 spinal root, with total removal 4 months later. In both specimens, most tumor cells were spindle-shaped. A few cells were large, epithelioid-like, with a prominent nucleolus. Mitoses were rarely seen. Many tumor cells contained coarse or fine granules of a brown pigment. Such cells were immunopositive for S-100 protein and HMB-45. Additionally, psammoma bodies were numerous in certain areas, indicating a diagnosis of psammomatous melanotic schwannoma (PMS). Periumbilical spotty pigmentation was found in the patient and in six of his siblings and their mother. The search for cardiac myxoma and endocrine overactivity was negative in the patient. Features of Carney's complex must be sought in a patient with PMS and in their primary relatives. So far, more than 150 patients and seven families with Carney's complex have been reported.

Spinal meningeal melanocytoma. Case report and analysis of diagnostic criteria

A case of cervical juxtamedullary meningeal melanocytoma is presented along with results of careful neuroradiological and pathological examinations. The authors review the previous literature and discuss the problems related to the intriguing diagnosis of this very rare entity. CT and MRI show variable appearances due to different degrees of melanization and do not reliably allow us to distinguish meningeal melanocytomas from other pigmented tumors. Pathological examination of the tumor is critical for diagnosis, but it absolutely must comprise electron microscopy and immunohistochemistry. Immunohistochemical and ultrastructural criteria are thus proposed to distinguish meningeal melanocytoma from pigmented meningioma or schwannoma and malignant melanoma (primary or secondary).

Intracranial meningeal melanocytoma: case report

A case of meningeal melanocytoma of the left sphenoid wing is reported and the other nine cases in the literature are reviewed. Meningeal melanocytoma is a benign melanotic tumor that derives from the melanocytes of the leptomeninges and may occur anywhere in the cranial and spinal meninges. Electron microscopy well demonstrates melanin and melanosomes within the tumor cells. The immunohistochemical pattern of this tumor includes strong positivity for S-100 protein, vimentin, and antimelanoma antibody and negativity for epithelial membrane antigen, neuron-specific enolase, cytokeratin, and glial fibrillary acidic protein. Complete surgical removal is the treatment of choice, whereas radiotherapy is usually unnecessary. In spite of benign biologic behavior of meningeal melanocytoma, the prognosis remains uncertain, because of the possible local recurrences.

Melanoma arising in a cervical spinal nerve root: report of a case with a benign course and malignant features

A 20-year-old caucasian woman with a 5-year history of right arm, neck, and back pain sought treatment when an automobile accident (4 months before admission) exacerbated her pain. Magnetic resonance imaging revealed an intra- and extradural mass compressing the spinal cord at the C5-C6 level. It also extended into and widened the neural foramen, mimicking a neurofibroma. A single cafe-au-lait spot was discovered in the inguinal region. A two-staged surgical resection was performed on an apparent hemorrhagic C6 nerve root mass. The mass exhibited diagnostic features of a malignant melanoma histologically, immunocytochemically, and ultrastructurally. A search for a primary lesion outside the nervous system or other metastases during an 8-year period from the onset of symptoms has been negative. The patient's chronic history, evidence of neural foraminal enlargement, and the absence of other malignant melanoma lesions or subsequent metastases indicates that this lesion may be a primary melanoma of the nerve root with a benign course.

Intracranial meningeal melanocytoma: a report of two cases and a review of the literature

Two rare cases of intracranial meningeal melanocytoma are reported with clinical, radiologic, and pathologic findings. In one of these the diagnosis was established by ultrastructural studies that showed premelanosomes and melanosomes in nonarachnoid-derived tumor cells. The other case was diagnosed retrospectively after a very long survival and is still alive 35 years after total excision and radiotherapy. The occurrence of these tumors in the cerebellopontine angle is rare as seen in our case.

Meningeal melanocytoma of the C8 nerve root: case report

A case of a meningeal melanocytoma involving the C8 nerve root is presented. The clinical symptoms and the radiological investigations resembled a neurinoma of the spinal nerve root. Intraoperatively the tumor was seen to be firmly attached to the dural covering of the dorsal nerve root. By using microsurgical technique, complete removal of the tumor with preservation of the ventral nerve root was accomplished. Histological examination revealed a typical meningeal melanocytoma as described by Limas and Tio in 1972. Ten additional cases of previously reported spinal meningeal melanocytomas are reviewed. The importance of differentiating this benign lesion from meningeal malignant pigmented tumors is stressed.

Retinoic acid- and staurosporine-induced bidirectional differentiation of human neuroblastoma cell lines

The differentiation pattern of two related human neuroblastoma cell lines, SK-N-SHF and SK-N-SHN, induced by retinoic acid and staurosporine was studied. Immunohistochemical and electron microscopic examination of the cells indicated that the SHF variant could undergo differentiation along a melanocytic route when treated with retinoic acid and to neuronal cells when treated with retionic acid and staurosporine together. Treatment of SHN cells with either or both these agents caused neuronal differentiation. The melanocytic pathway was characterized in part by the flattening of the cells, the appearance of melanocytic antigens and various forms of melanosomes, an increase in tyrosinase activity, and the absence of neuronal marker proteins. The neuronal route was typified by the development of long neuritic processes containing microtubules and numerous neurosecretory granules as well as by immunohistochemical reactions for neural cell adhesion molecule, synaptophysin, and neurofilament proteins. The significance of these results is discussed in terms of the differentiation responses of neuroblastoma cells to chemical agents as well as some of the factors involved in the regulation of phenotype expressions of these cells.

Meningeal melanocytoma: magnetic resonance imaging characteristics and pathological features. Case report

A case of meningeal melanocytoma at the foramen magnum is reported in a 62-year-old man. Magnetic resonance (MR) imaging revealed characteristic signal patterns: homogeneous high intensity on the T1-weighted image and low intensity on the T2-weighted image. Light microscopy showed a histological appearance similar to that of melanotic meningioma. The ultrastructural features of the neoplastic cells were compatible with those of melanocytes, but they contained no features of arachnoidal cells. Immunohistochemical bromodeoxyuridine study revealed low proliferative activity among the neoplastic cells. The MR appearance and pathological features in this rare case of meningeal melanocytoma are demonstrated and discussed.

Melanotic cerebral ganglioglioma: evidence for melanogenesis in neoplastic astrocytes

A composite melanotic glial-ganglionic tumor was resected from a 17-year-old girl who presented with a 5-year history of epilepsy. Grossly, the tumor was partly cystic, partly solid, located superficially in the temporal lobe. Histologically, its glial component was composed of spindle and pleomorphic cells, including tumor giant cells, which were associated with Rosenthal fibers, eosinophilic granular bodies and marked desmoplasia. The cells had immunohistochemical and ultrastructural features of astrocytes, and some were invested by incomplete basal lamina. Thus, the tumor had many features in common with pleomorphic xanthoastrocytoma. However, its most striking feature was the presence of melanin pigment in numerous neoplastic cells. Immunoelectron microscopy revealed glial fibrillary acidic protein-positive intermediate filaments in tumor cells bearing melanosomes and premelanosome, proving their astrocytic nature. This case demonstrates, for the first time, melanosomal melanogenesis in human cells with astrocytic phenotype, and provides additional evidence for the ability of central neuroepithelial cell derivatives to produce melanin.

Chronic progressive and relapsing neuromyopathy with massive dilatations of endoplasmic reticulum in muscle fibers

Large intracytoplasmic inclusions arising from the endoplasmic reticulum and nuclear envelope were found in the muscle fibers of a 32-year-old individual with a life-long, chronic and progressive sensory-motor neuropathy. The morphological features of the inclusions were similar to that occasionally reported in the striated muscles in several unrelated conditions as well as to "hyaline" or "colloid" inclusions commonly seen in motor neurons of the brain stem and spinal cord. The chemical nature of the inclusions is not known. Their occurrence in the muscle fibers is probably secondary to chronic denervation.