Vitiligo associated with malignant melanoma and lupus erythematosus

Acral manifestations of paraneoplastic and collagen vascular diseases

The skin often signals a number of systemic disease, making skin findings of paramount significance. Paraneoplastic diseases and collagen vascular diseases are vitally important illnesses. Paraneoplastic diseases and collagen vascular diseases may also occur with many different acral skin findings. Paraneoplastic skin diseases, associated with some cancers, are by definition nonmalignant skin disorders. These diseases can occur before, simultaneously, or after the diagnosis of cancer. Acral paraneoplastic diseases include acanthosis nigricans maligna, acquired pachydermatoglyphia, acrokeratosis paraneoplastica, palmoplantar keratoderma, and paraneoplastic nail disorders. Collagen vascular diseases include the acral skin findings of lupus erythematosus, scleroderma, dermatomyositis, and rheumatoid arthritis. Any acral skin finding may be encountered as the first finding of an undiagnosed malignancy or collagen vascular diseases. The role of the dermatologist is significant for often being the first physician to suspect a malignancy or collagen vascular disease.

Kikuchi-Fujimoto lymphadenitis imitating metastatic melanoma on positron emission tomography: a case report

BACKGROUND

Accurate staging is critical for decision-making for the treatment of malignant conditions. Fluoro-deoxy-glucose positron emission tomography-computed tomography (FDG PET-CT) is a highly sensitive imaging modality for the assessment of distant metastases; however false positive results are possible due to its lower specificity with detection of other hypermetabolic pathologies.

CASE PRESENTATION

A patient with high-risk thigh melanoma was staged with FDG PET-CT. Four ipsilateral inguinal nodes (three superficial, one deep) demonstrated intense hypermetabolic activity. Metastatic melanoma was confirmed in the largest superficial inguinal node with ultrasound-guided fine needle aspiration. Histopathology demonstrated metastatic melanoma in one superficial node and histiocytic necrotizing lymphadenitis, also known as Kikuchi-Fujimoto disease in five deep inguinal nodes.

CONCLUSION

This case illustrates a false positive FDG PET-CT due to coincidental, synchronous melanoma and Kikuchi-Fujimoto disease in the same draining lymph node basin.

Immunological basis of melanoma-associated vitiligo-like depigmentation

Vitiligo is a skin condition characterized by white, hypopigmented macules. Melanocyte loss is a feature of the disease, and it has been hypothesized that an autoimmune mechanism could be responsible for the depigmentation. Melanoma is a malignancy that develops in melanocytes; if not detected and treated early, it is often deadly. Leukoderma, a condition characterized by depigmentation of the skin, is sometimes associated with malignant melanoma. An immune response against melanocyte antigens leading to destruction of either melanoma cells or melanocytes has been observed in both vitiligo and melanoma. Studies in animal models and humans have shown that humoral and cell-mediated immune responses are involved in modulating cytotoxic activity against tumor cells and normal melanocytes. The study of factors associated with anti-tumor immunopathogenic mechanisms -autoimmunity for example- may provide us with tools for the diagnosis and treatment of diseases such as vitiligo and malignant melanoma.

Vitiligo-like primary melanoma

Depigmented or hypopigmented macules and patches have been described in association to primary and metastatic melanoma. Primary melanoma presenting at the onset as a vitiliginous patch without histopathological evidence of regression seems to be a rare event. We report 2 patients with melanoma in situ that expressed clinically as vitiligo-like patches and review the possible immunologic mechanisms responsible for this unusual presentation.