Malignant melanoma with a myxoid stroma: a diagnostic pitfall on fine-needle aspiration biopsy

Metastatic malignant melanoma mimicking a salivary gland basaloid neoplasm after treatment with nivolumab

Malignant melanoma is a well-known diagnostic pitfall, given its propensity to metastasize to different sites and mimic various entities. In this report, we present a fine-needle aspiration biopsy (FNA) of a metastatic melanoma with basaloid features that is occurring in the preauricular/parotid area. The patient is a 17-year-old male with a history of excision of melanoma of the left temple, and was undergoing adjuvant treatment with nivolumab. The prior excision was positive for S100, HMB-45, melan-A, and tyrosinase. On follow-up, he presented with non-FDG avid left preauricular area lesions. FNA was performed, and on-site evaluation demonstrated a cellular basaloid neoplasm with focal fibrillary stroma. Immunohistochemical stains revealed that the tumor cells were positive for SOX-10, S100, MITF, and HMGA2, and were negative for HMB-45, melan-A, tyrosinase, p63, cam 5.2 and PLAG1. The positive S100, SOX-10, and MITF results and negative cam 5.2 result supported the diagnosis of melanoma. Nivolumab was then stopped, Dabrafenib/Trametinib were started, and the patient underwent excision of the nodules. Nine-months later, he developed a rib metastasis that was positive for S100, SOX-10, melan-A, and tyrosinase. This report emphasizes that melanoma involving the parotid gland region has the potential to be misdiagnosed by FNA as a salivary gland neoplasm because of overlapping cytologic features and immunophenotypes. This pitfall is avoided by careful morphologic analysis and judicious use of ancillary studies.

Fine needle aspiration of malignant melanoma with myxoid features: A case report with molecular analysis

Malignant melanoma with myxoid features (MMM) is a rare melanoma variant in which tumor cells are embedded within a basophilic myxoid stroma. The stromal matrix is composed of acidic mucopolysaccharides, which are thought to be produced by mesenchymal stromal cells in response to melanoma invasion. Interestingly, this myxoid matrix is more often seen in metastasis from a primary tumor that does not have a myxoid stroma. The diagnosis of MMM on fine needle aspiration (FNA) can be confused with other myxoid tumors. Herein, we present a case of MMM diagnosed by FNA of a peri-auricular lymph node in an 89-year-old man with a history of resected malignant melanoma. We describe the clinical, cytohistological, and immunohistochemical findings, and present the unique molecular alterations that were identified. We also discuss the differential diagnosis and potential diagnostic pitfalls associated with MMM.

[Primitive myxoid melanoma: An unusual histological aspect]

BACKGROUND

Myxoid melanoma is a rare variant of melanoma that must be recognised. Herein we describe a new metastatic case.

PATIENTS AND METHODS

A 78-year-old woman consulted for a firm, pinkish nodule measuring 25mm and present for six months on her left leg. Analysis of the biopsy revealed achromic fusiform tumour cells separated by large myxoid plaques. Labeling of SOX10, HMB45 and PS100 was diffuse and of moderate to strong intensity. A diagnosis of myxoid melanoma was considered, with Breslow thickness of 9mm. Surgery was carried out with a 2-cm margin and confirmed the diagnosis. Dermatological follow-up at one year revealed metastatic spread to the ganglia, pleura, liver and bone.

DISCUSSION

Few cases of primary myxoid melanoma have been described, and the condition is probably underdiagnosed. The classic clinical presentation of this condition consists of a solitary achromic nodule found chiefly on the limbs. The microscopic appearance is relatively non-specific. Immunohistochemical analysis may indicate melanocytic involvement: cells exhibit expression of SOX10, diffuse expression of protein S100, and less consistent and more variable expression of HMB45. The increasingly common use of anti-SOX10 is of value since it is expressed in the nucleus of melanocytes. Mastocytes and TGF-ß secretion appear to be involved in myxoid stroma production. In the absence of specific codification, management of myxoid melanoma is comparable to that of other types of melanoma. There is uncertainty about the prognosis, with the involvement of TGF-ß possibly indicating the aggressive potential of this type of tumour.

Hypercellular round cell liposarcoma: A comprehensive cytomorphologic study and review of 8 cases

Background:

Myxoid and round cell liposarcomas (RCL) are low and high-grade counterparts of a common subtype of liposarcomas (LPS), representing a histologic continuum.

Aims:

The aim was to study the cytomorphology of hypercellular RCL and to look for features that differentiate RCL from other sarcomas displaying round cells with myxoid change.

Materials and Methods:

Eight cases of hypercellular RCL were identified retrospectively in which round cell component constituted greater than 75% of the area. Cytomorphological features were studied in detail.

Results:

Four cases were predominantly composed of round cells, out of which 2 were entirely composed of round cells. Myxoid metachromatic stroma was absent in 2 cases, while it was present in ample amounts in the remaining 6 cases. Spindle cells were completely absent in 5 cases and lipoblasts were observed in a single case of RCL. Plexiform vascular capillaries were seen in 4 cases. Adherence of neoplastic round cells around thin capillaries (ANAC) was observed in 7 cases.

Conclusions:

Plexiform capillary plexus and ANAC should be separately evaluated. The latter feature is the most consistent one, and is an important clue to the adipocytic nature of the neoplasm when hypercellular round cell areas are aspirated. Confident diagnosis of hypercellular RCL can be made on the basis of this feature. Lipoblasts, although specific, are seen in few cases. The rest of the features are nonspecific and useful only in combination.

Melanoma with second myxoid stromal changes after personally applied prolonged phototherapy

Most malignant melanomas are easily diagnosed; however, melanoma is also one of the lesions most frequently reported to mimic other tumors. One of the most difficult patterns to recognize is characterized by prominent myxoid matrix. A case is presented of primary cutaneous melanoma with abundant myxoid matrix in a patient who underwent prolonged phototherapy. Three years before, after getting sunburns, the patient noticed changes of a congenital nevus located in the area of sunburns. It became darker, started to blanch, and grew, with occasional bleeding. Without consulting a physician, the patient applied phototherapy onto the area for 30 months. He used a Bioptron lamp with polarized, polychromatic, incoherent light, at a wavelength from 480 to 3400 nm, without ultraviolet radiation. Clinically, the lesion was unevenly pigmented, ulcerated, covered with hemorrhagic crust, and measuring 3.5 cm in greatest dimension, with a satellite nodule. Multiple metastatic subcutaneous nodules were also found on the scalp and trunk. Histologically, the primary tumor and metastases were composed of nests and pseudotubular formations of polygonal, spindle, and stellate cells embedded in abundant myxoid stroma that comprised more than 80% of the tumor mass. Focally, in the epidermis and papillary dermis, nests of atypical melanocytes and numerous melanophages were observed. Chemotherapy and immunotherapy were administered as suggested by an oncologist. The patient died from distant metastases 6 months after the diagnosis. Although some authors believe that myxoid changes do not seem to alter the behavior of melanoma, it remains an important differential diagnosis issue.

Fine-needle biopsy as a diagnostic technique for metastatic melanoma

Fine-needle biopsy (FNB) is a rapid, minimally invasive technique, widely used for the investigation and diagnosis of lesions in a variety of body sites. It is a procedure with high diagnostic accuracy for metastatic melanoma, with a sensitivity of 92.1% and a specificity of 99.2% in a recent large study. Although at present FNB has virtually no role in the initial diagnosis of pigmented primary cutaneous tumors, recent evidence suggests that it should be the first-line diagnostic modality for confirmation of clinically and/or radiologically suspected metastases in melanoma patients. As the specimen procured by FNB can be examined within minutes of performing the procedure, an on-demand FNB service with rapid communication of results to the patient's treating clinician enables a more efficient and cost effective approach to the multidisciplinary management of melanoma patients. In the future, it is likely that molecular analysis of very small amounts of tumor tissue obtained by FNB will provide an accurate estimate of prognosis and will facilitate selection of patients who may benefit from targeted molecular therapies.

Malignant melanoma in the 21st century, part 1: epidemiology, risk factors, screening, prevention, and diagnosis

Malignant melanoma is an aggressive, therapy-resistant malignancy of melanocytes. The incidence of melanoma has been steadily increasing worldwide, resulting in an increasing public health problem. Exposure to solar UV radiation, fair skin, dysplastic nevi syndrome, and a family history of melanoma are major risk factors for melanoma development. The interactions between genetic and environmental risk factors that promote melanomagenesis are currently the subject of ongoing research. Avoidance of UV radiation and surveillance of high-risk patients have the potential to reduce the population burden of melanoma. Biopsies of the primary tumor and sampling of draining lymph nodes are required for optimal diagnosis and staging. Several clinically relevant pathologic subtypes have been identified and need to be recognized. Therapy for early disease is predominantly surgical, with a minor benefit noted with the use of adjuvant therapy. Management of systemic melanoma is a challenge because of a paucity of active treatment modalities. In the first part of this 2-part review, we discuss epidemiology, risk factors, screening, prevention, and diagnosis of malignant melanoma. Part 2 (which will appear in the April 2007 issue) will review melanoma staging, prognosis, and treatment.

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.