Malignant melanotic schwannoma of the bronchus

Magnetic resonance imaging features and clinical course of malignant melanotic nerve sheath tumors: single institution experience over two decades

OBJECTIVE

To evaluate MR features and clinical course of malignant melanotic nerve sheath tumor (MMNST), previously known as melanotic schwannoma and considered indolent and rarely metastasizing.

MATERIALS AND METHODS

This IRB-approved retrospective study searched 31 patients (20 male: 11 female, mean age 48; range 15-76) with histologically confirmed MMNST in a single tertiary cancer center over 22 years. Pre-treatment MR was available in 12 patients and evaluated by two radiologists in consensus regarding lesion location, size, morphology, signal characteristics, contrast enhancement, local invasion, and presence of classic signs of peripheral nerve sheath tumors. Clinical outcomes, including local recurrence, metastasis, and survival, were examined in 12 patients for whom follow-up was available.

RESULTS

The spine was the most frequent site (13/31) among all identified cases. In 12 cases with MR, lesions were well-circumscribed in 11/12 cases, with a mean size of 4.5 cm (2.3-13.0 cm). Ten of 12 cases showed T1 hyperintensity. In 5/9 spinal MRI, tumor involved multiple levels. All lesions showed contrast enhancement, and local bone invasion in > 50%. A dumb-bell shape was common to all spinal lesions. Classical signs of nerve sheath tumors were uncommon. Among 12 patients with a mean follow-up of 4.8 years (range 1.3-10.2 years), six were disease-free, while two had recurrence or metastases, and four had died of metastases.

CONCLUSION

MMNST usually presents as a T1 hyperintense enhancing dumb-bell shaped mass in the spine. Multi-level involvement and bone invasion are common. MMNST is clinically aggressive with high rates of metastases and death.

Primary bronchial schwannoma: A case report

RATIONALE

Bronchial schwannomas are extremely rare among the benign tracheobronchial tumors and little are known about its epidemiology and optimal clinical management. Here, we report a case of bronchial schwannoma in a young Japanese man and clinical implications about epidemiology, symptom, diagnosis, and treatment of bronchial schwannoma.

PATIENTS CONCERN

A 37-year-old man visited our department with a nodule incidentally found on his chest radiograph during a routine medical checkup.

DIAGNOSIS

The tumor was diagnosed as a bronchial schwannoma after pathological evaluation. Microscopically, the tumor consisted of spindle cell proliferation characterized by an alternating highly ordered cellular Antoni A component with occasional nuclear palisading and a loose myxoid Antoni B component. Tumor cells were immunoreactive for S100 but not for smooth muscle actin or KIT.

INTERVENTIONS

A video-assisted right middle and lower bilobectomy was performed.

OUTCOME

He remains under observation without recurrence.

LESSONS

In our review, many reports have come from Asian countries. Bronchial schwannoma can occur within a wide range of age groups and in both men and women. No difference in incidence was observed between right and left bronchial tree. Bronchial schwannoma is sometimes difficult to differentiate from malignant diseases. We should include bronchial schwannoma as one of the differential diagnoses of primary bronchial tumors.

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.

Malignant melanotic nerve sheath tumor in pleural effusion: Deceitful cytology with significant repercussions

Malignant melanotic nerve sheath tumor (MMNST) is an exceedingly rare and aggressive neoplasm of Schwann cell origin that has seldom been described in the cytopathology literature. Herein we present a case of a 60-year-old female with a 3.8 cm presacral mass that was diagnosed as a MMNST. A molecular workup demonstrated TERT promoter -124C > T and TET2 Q891* gene mutations. Within 2 years of her initial diagnosis, she had developed widespread metastasis and pleural effusions. A cytologic workup of the pleural fluid revealed clusters of vacuolated epithelioid cells with enlarged nuclei, prominent nucleoli, and occasional multinucleation. The lesional cells were positive for SOX10, S100-protein, Melan-A, and HMB45, while negative for Calretinin, MOC31, and monoclonal CEA. In this clinicopathologic context, a diagnosis of metastatic MMNST was rendered. Awareness of this entity and its clinical presentation, along with a critical understanding of its molecular findings and that of imitators, is crucial in achieving an accurate diagnosis.

Endobronchial schwannoma in adult: A case report

Schwannomas are uncommon benign nerve sheath tumors and often arise in the posterior mediastinum and costovertebral angle. However, endobronchial schwannomas are rare. In fact, there are only a few reported cases in the literature. Here, we describe a case of an endobronchial schwannoma causing obstruction of the right upper lobe bronchus.

Brain and spine melanotic schwannoma: A rare occurrence and diagnostic dilemma

PURPOSE

Melanotic schwannoma (MS) was formerly known as a rare variant of schwannoma. The behavior of MS is unpredictable, with a tendency for recurrence and metastasis. The purpose of this study was to illustrate the imaging characteristics of these rare and misdiagnosed tumors. The prognosis of MS is discussed, along with the importance of follow-up exams to assess for recurrence and metastasis. Furthermore, we compare our results with those previously published on MS in order to have a better understanding of this rare entity.

METHODS

Three MS cases were encountered between 2008 and 2015 at our institute. All available data were reviewed, including the clinical history, imaging findings, operative notes, and the histopathology results. A follow-up magnetic resonance imaging (MRI) scan was also reviewed up to 23 months post surgery to assess for recurrence.

RESULTS

Three cases of MS are included: one in the brain and two in the spine. The brain lesion was in the occipital region. The spine lesions were thoracic intramedullary and sacral intradural. All cases were hypointense on T2-weighted imaging. Gross total resection was achieved for all lesions without adjuvant therapy. To date, the brain lesion recurred 15 months after surgery.

CONCLUSIONS

MS is a rare and distinct entity rather than a variant of schwannoma, and it poses both diagnostic and management dilemmas. Although MS has characteristic MRI features, including T1 and T2 shortening, the preoperative diagnosis is always challenging. Accurate diagnosis is crucial for management planning, including long-term follow-up exams to assess for recurrence and metastasis.

Left lower lobe sleeve resection for endobronchial schwannoma

Schwannomas are mesenchymal neoplasms originating from Schwann cells of the nerve sheath. The tumor may appear anywhere in the body, while it has a predilection for extremities, trunk, retroperitoneum, head, and neck. Primary pulmonary schwannoma is extremely rare, accounting for less than 0.2% of all lung tumors. A 42-year-old man was incidentally discovered to have an endobronchial tumor, and we performed the left lower lobe sleeve resection to remove the mass completely. Postoperative histopathological findings confirmed a benign schwannoma. Although endobronchial schwannoma is extremely rare, follow-ups are crucial for monitoring tumor growth and reducing the risk of recurrence.

What Tactics Should a Surgeon Choose to Treat a Black Extracerebral Tumor? A Case Report of Psammomatous Melanotic Schwannoma of the Meckel Cave and Literature Review

BACKGROUND

Neoplasms located in the Meckel cave account for 0.2%-0.5% of all intracranial tumors. This area is the site of many types of pathologic lesions, most often trigeminal nerve schwannomas and meningiomas. Melanin-containing tumors are rare in this area. These tumor types can be suspected if the magnetic resonance characteristics of a tumor has some differences in comparison with other types of central nervous system neoplasms. In fact, differential diagnosis of melanotic tumors is based mainly on the histopathologic criteria and immunohistochemical profile. This article presents a case report of melanotic schwannoma of the Meckel cave and a literature review of the problem.

CASE DESCRIPTION

A 23-year-old man underwent a 2-stage surgery for a dumbbell pigmented mass lesion located in the Meckel cave. No signs of recurrence were seen on follow-up magnetic resonance imaging (MRI) 3.5 years after the operation.

CONCLUSIONS

Melanin-containing tumor can be suspected in the presence of radiologic characteristics, such as a hyperintense MRI signal on T1-weighted images and a hypointense signal on T2-weighted images. If a black extracerebral tumor is detected, the main course of surgical treatment is maximal excision despite it possibly being a malignant melanoma and the temptation to perform partial resection because of an unfavorable prognosis. Chemotherapy can be justified in the presence of an aggressive melanotic schwannoma.

Pathology of Melanotic Schwannoma

CONTEXT.—

Melanotic schwannoma (MS) is a nerve sheath tumor with a uniform composition of variably melanin-producing Schwann cells and metastatic potential. The MS is an uncommon neoplasm, accounting for less than 1% of all nerve sheath tumors, with a predilection for spinal nerve involvement. Microscopically, the tumors are characterized by spindle and epithelioid cells arranged in interlacing fascicles, with marked accumulation of melanin in neoplastic cells and associated melanophages. The MSs are frequently associated with Carney complex, showing features of psammoma bodies and adipose-like cells. Strict criteria of malignancy in MS are not well developed, although a combination of worrisome histologic features (large, vesicular nuclei, with macronucleoli, brisk mitotic activity, and necrosis) raises concern for aggressive behavior.

OBJECTIVE.—

To review the current status of the MS literature, discussing putative etiology, histopathology, current genetics, and differential diagnoses, including overlap with other pigmented tumors.

DATA SOURCES.—

Search of PubMed (National Center for Biotechnology Information, Bethesda, Maryland) and the authors' own experiences.

CONCLUSIONS.—

The occurrence of MS at several unusual anatomic sites and its spectrum of morphologic patterns can result in significant diagnostic difficulty, and correct diagnosis is particularly important because of its high tendency to recur locally and to metastasize, which highlights the importance of diagnostic recognition, ancillary molecular genetic testing, and close clinical follow-up of patients with MS.

A Rare Case of Aggressive Melanotic Schwannoma Occurred in Spinal Nerve of a 59-Year-Old Male

Melanotic schwannoma (MS) is a rare variant of nerve sheath neoplasm that shows ultrastructural and immunophenotypical features of Schwann cells but also has cytoplasmic melanosomes and is reactive for melanocytic markers as well. Unlike conventional schwannoma, which is totally benign, MS has an unpredictable prognosis and is thought to have low-malignant potential. Herein, we present a rare case of recurrent MS in lumbar spine of a 59-year-old male.

Consistent copy number changes and recurrent PRKAR1A mutations distinguish Melanotic Schwannomas from Melanomas: SNP-array and next generation sequencing analysis

Melanotic Schwannomas (MS) are rare tumors that share histological features with melanocytic tumors and schwannomas. However, their genetics are poorly understood. To elucidate the genetic characteristics of MS, we performed genome-wide studies in a series of cases. Twelve MS cases were available for the study. Genomic DNAs extracted from formalin-fixed paraffin embedded tumor tissues were subjected to copy number (CN) and allelic imbalance (AI) analysis by Single Nucleotide Polymorphism (SNP)-array and screened for mutations in coding exons of 341 key cancer-associated genes using a hybrid capture-based next-generation sequencing (NGS) assay. Sanger sequencing was used to further verify recurrent mutations detected by NGS study. SNP-array analysis revealed remarkably stereotypic chromosomal abnormalities in MS. Hypodiploidy was common, typically involving monosomies of chromosomes 1, 2, and 17. All 12 samples showed mutations in PRKAR1A gene, including 2 cases with 2 mutations each. The 14 mutations were scattered across PRKAR1A, and most were inactivating mutations. AI on 17q, presenting as loss of heterozygosity with or without CN losses, combined with a PRKAR1A mutation was observed in 9/12 MS cases. The remaining 3 cases included the two samples harboring two mutations in PRKAR1A. MS exhibits a stereotypic pattern of chromosomal losses. In contrast, melanomas are typically characterized by the presence of multiple CN aberrations, without demonstrable differences in the frequency of losses and gains. Inactivation of both alleles of PRKAR1A by "two hits" observed in almost all cases underscores the central role of PRKAR1A in the pathogenesis of this neoplasm. © 2015 Wiley Periodicals, Inc.

Malignant psammomatous melanotic schwannoma of the spine: A component of Carney complex

BACKGROUND

Psammomatous melanotic schwannomas (PMS) of the spine may be a component of the Carney complex in 50% of cases and is inherited in an autosomal dominant manner. Most PMS are benign and frequently associated with lentiginous pigmentation; cardiac, cutaneous, or breast myxomas; endocrine overactivity; and cutaneous blue nevi. These tumors are characterized by melanin containing cells having ultrastructural characteristics of Schwann cells.

CASE DESCRIPTION

Two patients had spinal PMS that were surgically resected with adjacent local radiotherapy, followed by local recurrence and metastasis. The aggressive nature of this tumor is reported.

CONCLUSION

Spinal PMS are rarely malignant with local recurrence and distal metastases. Inquiry into the patient's and family members' hereditary background for the Carney complex is important to avoid overlooking potential lethal associated abnormalities.

A muscle mass in a patient with polymyalgia rheumatica

We report the extremely uncommon case of a 77-year-old woman in whom a tumor found to be a melanotic schwannoma, arising from the right rectus abdominis muscle, was detected during investigation for a rheumatic disorder, finally identified as polymyalgia rheumatica (PMR). Tumors of this type most commonly occur in spinal nerve roots, and their clinical behavior is very difficult to predict. As far as we are aware, this is the first reported case affecting the aforementioned site. The challenging issue in this case concerns the possible link between the 2 clinical conditions, in particular the development of PMR as a paraneoplastic syndrome. Although such an association has not been reported, PMR is included among the rheumatic disorders reported to be associated with malignancies and occasionally with benign tumors. However, given that tumor resection did not result in remission of PMR and symptoms improved rapidly with prednisone, it seems likely that the above disorders might simply coexist.

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).

Melanotic schwannoma with drop metastases to the caudal spine and high expression of CD117 (c-kit)

Melanotic schwannomas (MS) are tumors of Schwann cell origin characterized by cytoplasmic deposition of melanin. The authors present the case of a 61-year-old man who experienced progressive weakness of the lower extremities over 2 years. This was followed by acute deterioration, which prompted his presentation. MRI of the spine revealed an intradural, extramedullary lesion at the level of T7 with severe spinal cord compression. More caudally, there was involvement of the lumbar spine with drop metastases to the conus medullaris and cauda equina. The patient underwent thoracic laminectomy for tumor resection. A diagnosis of MS was made based on histologic morphology, immunohistochemical profile, and ultrastructural findings. In this report, the authors describe a MS with expression of CD117 (c-kit) and review the literature pertaining to this condition.

Massive hemoptysis caused by endobronchial schwannoma in a patient with neurofibromatosis 2

Neurogenic tumor of the lung is very uncommon. To the best of our knowledge, endobronchial schwannoma complicated by massive hemoptysis in a patient with neurofibromatosis 2 has not been reported previously. We report a case of endobronchial schwannoma complicated by massive hemoptysis in an 18-year-old man with neurofibromatosis 2. The diagnosis of neurofibromatosis 2 was established by demonstration of bilateral vestibular schwannomas on magnetic resonance imaging of the brain and pathologic examination of the resected brain tumors. Massive hemoptysis developed after surgical removal of the brain tumors in this patient. Bronchoscopy was done immediately after the first episode of hemoptysis and a tumor protruding from the orifice of the right lower lobe bronchus was found. Despite 2 additional bronchoscopies to stop bleeding and ameliorate airway obstruction in the consecutive 2 days, hemoptysis recurred rapidly and caused profound oxygen desaturation. The patient was subjected to right lower lobectomy and endobronchial schwannoma was evidenced pathologically.

Psammomatous melanotic schwannoma: presentation of a rare primary lung tumor

A 30-year-old nonsmoking man underwent a left lower lobectomy with bronchoplasty for an obstructing lesion of the left lower lobe. Pathology results demonstrated a psammomatous melanotic schwannoma, a rare pigmented neural tumor of which only 25 cases have been reported as originating in the respiratory tract.

Spinal melanotic schwannoma: a tumour with poor prognosis

AIM

To clarify the prognosis of melanotic schwannoma. This is a rare tumour which is generally considered as a benign lesion, reported in many cases with a short follow-up only.

METHODS AND RESULTS

Five cases of spinal melanotic schwannoma were retrospectively studied. The tumours were examined using standard histological, immunohistochemical and ultrastructural methods. No features of malignancy (high mitotic count, atypia or necrosis) were found in the primary tumours. The follow-up period ranged from 3 to 7 years. Malignant clinical behaviour was clear-cut in four cases: three patients died from metastases to various sites and one presented several discrete spinal tumours of the same type seven years after the first operation. Only one patient presented no recurrence and was free of disease 6 years after initial diagnosis. The review of 57 cases of the literature (including our cases), showed that 15% of the cases had recurrences and 26.3% were complicated by metastasis. Only 53% of the cases followed for more than 5 years, were free of disease vs. 67.5% of the cases with shorter follow-up. Twenty additional cases had no follow-up.

CONCLUSION

Appropriate long-term follow-up is required for all melanotic schwannomas, as it may recur or metastasize after more than 5 years, even in the absence of overt malignant histological features.

Primary pulmonary ganglioneuroblastoma: a clinicopathologic and immunohistochemical study of two cases

We present two patients with primary ganglioneuroblastoma involving the bronchial wall. The first, a 38-year-old woman, presented with signs and symptoms suggestive of multiple endocrine neoplasia, including gastric ulceration and hypercalcemia. Chest radiographic studies revealed a 3-cm nodule in the hilus of the right lung and two less-pronounced lesions in the periphery of the right lung. The second, a 20-year-old asymptomatic woman, was evaluated for a solitary mass in the upper lobe of the left lung that was peribronchial and that impinged on the lumen of a bronchus. Grossly, both neoplasms extended from bronchi, were well-circumscribed, firm, tan or white, and homogeneous, and measured 5 x 5 cm and 3 x 3 cm, respectively. Histologically, both tumors were characterized by neuroblastoma with areas of neuropil and multifocal areas of ganglion cells. Immunohistochemical studies performed in one case showed focal staining for neurofilament protein and S-100 protein and diffuse staining for neuron-specific enolase. Follow-up information showed that one patient died a few days after admission to the hospital; the second patient has remained well and without evidence of recurrence or metastases 1 year after initial diagnosis. These two cases confirm that ganglioneuroblastoma can occur as a primary pulmonary tumor in adults, presumably arising from sympathetic ganglia of the bronchus.

Malignant melanotic schwannoma fine-needle aspiration biopsy findings

We describe the cytologic, histologic, and clinical features of two cases of melanotic schwannoma, arising in the neck and superior mediastinum, respectively. Cytologic findings in both cases included the presence of cells with heavily pigmented cytoplasm, showing long branching projections. The cells were arranged in clusters, with ill-defined boundaries. Histologic findings included interlacing fascicles of cells, with abundant melanin pigment, calcification, and necrosis. Immunohistochemical stains were positive for S. 100 protein and anti-human melanoma (HMB45). Both patients died with metastases.

Primary melanoma of the lung: a clinicopathologic and immunohistochemical study of eight cases

Primary malignant melanoma of the lung (PMML) is an uncommon neoplasm that may be confused with more conventional types of lung cancer. Although the previously proposed criteria for diagnosis, including the presence of an in situ component, are often difficult to satisfy, this lesion is characterized by a poor prognosis, ultimately leading to patient death. We report eight cases of PMML that presented as solitary, central endobronchial neoplasms, resulting in a picture that closely resembled carcinoid tumor or poorly differentiated non-small-cell carcinoma of the lung. The mean age at diagnosis was 51 years (range 45-71). The patients included one woman and seven men. The histologic growth pattern varied from organoid to fascicular and included epithelioid to spindled cells with hyperchromatic to vesicular nuclei, prominent eosinophilic nucleoli, and abundant eosinophilic to clear cytoplasm with occasional intranuclear cytoplasmic inclusions. A bronchial in situ component was present in four cases. Initial interpretations included carcinoid tumor, non-small-cell carcinoma, and malignant melanoma. Melanin was present in all neoplasms on hematoxylin and eosin staining, although very focally in one case, and was Fontana-Masson positive in all cases. Immunohistochemically, diffuse strong positivity for S-100, HMB-45, and vimentin was present in all seven tumors tested. All seven tumors were negative for cytokeratin, CAM 5.2, and chromogranin. Ultrastructural examination of the eighth case showed dysmorphic premelanosomes but no neurosecretory granules. None of the patients had disseminated disease at presentation, and all patients underwent surgical resection (seven lobectomies and one excision). In this series, primary malignant melanoma of the lung was characterized by an aggressive postoperative course, with five patients dying of metastatic disease from 4 to 32 months after resection (median 14 months). Two patients are alive with metastatic disease at 4 and 30 months after surgery, and the eighth patient is alive with no evidence of disease 108 months after surgery at last follow-up. Metastatic melanoma was identified in various sites, including the lungs, adrenal glands, liver, mesentery, brain, and bone. The cases herein presented indicate that PMML should be included in the differential diagnosis of primary bronchial tumors.

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.

Primary pulmonary tumours of nerve sheath origin

Primary intrapulmonary tumours of nerve sheath origin are extremely rare. We describe the clinicopathological features of four such peripheral nerve sheath tumours, two benign and two malignant. Of the benign tumours, one was a typical schwannoma and the other an ancient or degenerated schwannoma. The typical schwannoma was endobronchial in origin, diagnosis being established by small bronchoscopic biopsy. The histological diagnosis of malignant peripheral nerve sheath tumour required immunohistochemical and/or ultrastructural evidence of nerve sheath differentiation. One malignant tumour arose in a patient with Von-Recklinhausen's disease. Both malignant tumours behaved aggressively with the development of multiple intrapulmonary metastases, despite the markedly different histological appearance of the two tumours. Flow cytometric analysis of nuclear DNA content was performed on the four tumours, all of which showed a diploid DNA profile.

CT and MR imaging of melanocytic schwannomas; report of three cases

Melanocytic Schwannomas are rare tumours which can arise in soft tissues, spinal nerve roots and in the central nervous system. The literature suggests that they have a malignant behaviour with local recurrence after surgery. We present three patients with this lesion, two in the thoracic spine and one in the head of the pancreas. The clinical outcome in these cases has been disappointing, since two patients died from complications due to local spreading of the tumour in spite of surgery and radiotherapy. CT could not distinguish these tumours from other neurogenic neoplasms. When these tumours occur near the vertebral body, CT could only detect early bone erosion. MR findings show promising features, with a high signal on T1-weighted images, due to melanin. However, more experience is necessary to establish the possible specific features of melanocytic Schwannomas in MRI.