Discohesive malignant melanoma simulating a bullous dermatoses.

Area of Science:

• Dermatopathology
• Oncology
• Immunology

Background:

• Malignant melanoma presents with diverse clinical and histological features.
• Unusual variants include balloon cell, signet ring cell, and myxoid changes.
• Acantholysis is an uncommon histopathological feature in malignant melanoma.

Purpose of the Study:

• To describe two unique cases of malignant melanoma with extensive melanocytic discohesion in an acantholytic pattern.
• To highlight the diagnostic challenges and potential pathogenetic mechanisms of this rare melanoma variant, termed 'discohesive melanoma'.
• To differentiate 'discohesive melanoma' from pemphigus vulgaris and other conditions.

Main Methods:

• Histopathological examination of two cases of malignant melanoma with acantholytic features.
• Routine direct immunofluorescence studies for pemphigus-related antibodies (IgG, C3).
• Indirect immunofluorescence and immunosorbent assay for desmoglein autoantibodies.

Main Results:

• Both cases showed extensive melanocytic discohesion mimicking pemphigus vulgaris.
• Direct immunofluorescence studies for pemphigus antibodies were negative.
• One case demonstrated positive antibodies to desmoglein 1 via immunosorbent assay, despite negative indirect immunofluorescence.

Conclusions:

• 'Discohesive melanoma' represents a rare histopathological variant of malignant melanoma.
• Distinguishing 'discohesive melanoma' from pemphigus vulgaris requires careful clinicopathological correlation and specific immunodiagnostic testing.
• Further research into the pathogenetic mechanisms of melanocytic discohesion in melanoma is warranted.