Immunophenotyping of amelanotic melanoma. A case report

Amelanotic malignant melanoma (AMM) is a subtype of cutaneous melanoma with little or no pigment upon visual inspection. The lack of pigmentation is the reason for late diagnosis of lesions and a poor prognosis. We report a case of a 55-year-old female with an AMM diagnosed by immunophenotyping. Monoclonal antibodies S-100, HMB-45, and antibodies to cytokeratin were used. Our patient underwent a wide local excision (a 2 cm wide margin) 2 years ago. So far there are no signs of a recurrence. In doubtful cases, immunophenotyping with monoclonal antibodies HMB-45 and S-100 is important for confirming the correct diagnosis of AMM.     

A case of subungual amelanotic malignant melanoma: an electron microscopic study of aberrant melanosomes

A 68-year-old woman with amelanotic malignant melanoma (AMM) of her left thumbnail bed was reported. The tumor cells were positive with S-100 protein. Electron microscopic findings revealed the presence of typical melanosomes and a variety of aberrant melanosomes within the tumor cells, obviously different from the results for common malignant melanoma.     

Atypical fibroxanthoma-like amelanotic malignant melanoma: A case report and literature review

Atypical fibroxanthoma (AFX)-like malignant melanoma is very rare. Here, we report a case of amelanotic AFX-like melanoma in a 72-year-old Taiwanese woman presenting with two separate, asymptomatic, enlarging erythematous nodules within a large hypopigmented patch on her left cheek. Histologically, both lesions showed cellular nodules in the reticular dermis separated from the overlying flattened epidermis by a zone of solar elastosis or fibrosis. The tumor consisted of sheets of atypical epithelioid cells arranged in a vague nesting pattern, as well as many atypical large or gigantic cells with one or more, large hyperchromatic, vesicular, or pleomorphic nuclei with prominent nucleoli, and moderate-to-abundant eosinophilic or foamy cytoplasm. Focal intraepidermal proliferation of atypical melanocytes with a pagetoid pattern was found only in the periphery of the main tumor. The tumor cells were moderately to strongly positive for S-100, Melan-A, and HMB-45. The pleomorphic giant cells were focally CD68-positive but CD163-negative. The patient underwent tumor excision followed by radiotherapy due to the narrow surgical margins. A sentinel lymph node biopsy revealed no metastasis of the melanoma. This case illustrates the importance of scrutinizing any subtle proliferation of atypical melanocytes in the epidermis in an AFX-like tumor in order to avoid misdiagnosis.     

皮肤镜表现为玫瑰花瓣征及精子样血管的瘢痕一例

玫瑰花瓣征和精子样血管都是相对少见的皮肤镜表现,临床医生常认为是日光性角化病和早期蕈样肉芽肿的特异性表现,本文报道一例外伤后瘢痕皮肤镜检查见玫瑰花瓣征和精子样血管,提示此两种结构可能为非特异性皮肤镜表现。     

Dermoscopic clues in the diagnosis of amelanotic and hypomelanotic malignant melanoma

The clinical identification of amelanotic malignant melanoma (AMM) and hypomelanoticmalignant melanoma (HMM) becomes difficult due to the lack of pigmentation and to thediverse clinical presentations. Dermoscopy is very useful in these cases, increasingthe level of suspicion of malignancy. We report 4 cases of amelanotic malignantmelanoma and hypomelanotic malignant melanoma with characteristic dermoscopicfindings. Dermoscopy under polarized light demonstrates vascular polymorphism,globules and milky-red areas, in addition to chrysalis and multiple blue-graydots.     

31-P-spectroscopy as a method for studying biochemical changes in skin tumors: exemplified by malignant melanoma and squamous cell carcinoma

We report on the basic principles concerning in vivo P-31 MR spectroscopy and give a short review of the corresponding studies on skin tumors described in the literature. Malignant melanoma and squamous cell carcinoma are both characterized by high concentrations of phosphomonoester and phosphodiester. By means of the P-31 spectroscopy technique, we are able to detect changes regarding the tumor metabolism as a response to chemotherapy, irradiation, or biological immune modifiers (e.g. interferon).     

Cerebriform nodular amelanotic metastases of malignant melanoma: a challenge in differential diagnosis of a rare variant

High variability of the clinical appearance of malignant melanoma (MM) and its metastases render the differential diagnosis of solid amelanotic tumours difficult. We report a 71-year-old woman with several unusual cutaneous tumours of cerebriform morphology, suggesting skin metastases from occult internal cancer. Histopathological findings and thorough investigations, however, revealed a late-stage metastatic MM. We discuss the differential diagnosis of skin metastases of various origin and underline the difficulties for early detection of MM.     

Expression of glutathione S-transferase-pi in malignant skin tumors.

GST-pi has been known to be markedly increased in human (pre) neoplasms of several organs. In this paper, the significance of immunohistochemical detection of GST-pi in human malignant tumors of the skin was studied. In specimens from 40 patients with various skin cancers, malignant melanoma, Paget's disease and undifferentiated squamous cell carcinoma showed strong reactivity in GST-pi staining. The reactions were negative or weak in Bowen's disease, basal cell epithelioma and solar keratosis. In normal melanocytes, eccrine, apocrine, and breast gland cells stained positively but not in keratinocytes, sebaceus gland and fibroblasts. While immunohistochemical detection of GST-pi in the skin was not specific for malignancies, it contributed to aid the distinction of squamous cell carcinoma from other keratinocytic tumors. GST-pi might provide potentially useful information on chemosensitivity of skin cancer, and might serve as a biomarker of disease activity.     

Osteosarcomatous changes in malignant melanoma. Immunohistochemical and ultrastructural studies of a case

Immunohistochemical and ultrastructural studies were conducted to elucidate the nature and origin of osteosarcomatous changes in malignant melanoma in a 43-year-old Japanese man. Immunohistochemical studies with the use of antisera against human S-100 protein and neuron-specific enolase demonstrated positive reactions in the tumor cells within the osteosarcomatous area. Ultrastructurally, the neoplastic cells showed marked similarities to those from osteosarcomas. Additionally, occasional neoplastic cells contained round or ellipsoidal osmiophilic organelles, presumably melanosomes. These findings indicate that osteosarcomatous changes in malignant melanoma are produced by the dedifferentiated melanoma cells.     

A case of pedunculated malignant melanoma of the vaginal mucosa.

We report an 84-year-old Japanese woman who presented with a pedunculated malignant melanoma of the vaginal mucosa. Mucosal melanoma is believed to be more common in Japan than other countries, but such tumors of the vulvovaginal region are quite unusual. In our patient, three tumors were connected by a narrow pedicle. Three black tumors measuring 5-10 mm in diameter with a common pedicle were seen on the vaginal mucosa at five o'clock from the cervix. The tumors were hanging from the narrow pedicle. On histologic examination, they were diagnosed as malignant melanoma. Resection was done with a distal margin of 3 cm from the tumors and a margin of 1 cm from the cervix. The patient has had no evidence of local recurrence or distant metastasis. In our patient, the three main tumors had a common pedicle, which seems to be a unique finding. Since pedunculated malignant melanomas are rare, making a clinical diagnosis is difficult. Although pedunculated melanomas are recognized as having a high malignant potential because these lesions are generally thick, a relatively good outcome is sometimes reported. In our patient, there was no tumor infiltration into the dermis of the pedicle, and this may be one reason for the good outcome at present. There has been no previous report of a mucosal melanoma consisting of three tumors like those in the present patient.     

Detection of clinically amelanotic malignant melanoma and assessment of its margins by in vivo confocal scanning laser microscopy.

BACKGROUND: Near-infrared confocal scanning laser microscopy (CSLM) represents a novel imaging technique for in vivo microscopic analysis of skin lesions, including pigmented lesions. OBJECTIVES: To investigate the feasibility of detecting a clinically amelanotic malignant cutaneous melanoma using CSLM and to explore the use of this technique for assessing its margins. PATIENTS AND METHODS: Two lesions from 2 patients were imaged and analyzed using CSLM. Sites suspected to represent melanoma or benign skin on CSLM were marked as such; then, biopsy specimens were obtained for diagnosis using conventional histological analysis. Both lesions were stained for melanin pigment and analyzed immunohistochemically for the expression of melanosomal markers. In 1 case, a biopsy specimen was also examined with electron microscopy. RESULTS: The images obtained using CSLM allowed recognition of an abnormal intraepidermal melanocytic proliferation that was distinctly different from normal skin. Comparison of the sites examined using CSLM and subsequently using conventional histological methods revealed that CSLM correctly identified intraepidermal melanoma and benign skin. Fontana-Masson stains and immunohistochemical and ultrastructural studies showed that clinically amelanotic melanoma cells contained melanosomes and rare melanin granules. CONCLUSIONS: We demonstrated, for the first time, the detection of clinically amelanotic melanoma using CSLM. This technique may aid in the early detection of clinically barely visible or nonpigmented melanomas and may facilitate preoperative noninvasive assessment of their margins.