Epidermoid cyst with sweat ducts on the torso

Area of Science:

• Dermatopathology
• Histology
• Immunohistochemistry

Background:

• Epidermoid cysts are common skin neoplasms.
• Previous reports have identified eccrine duct differentiation in epidermoid cysts of the palmoplantar region.
• The origin and differentiation potential of epidermoid cysts are areas of ongoing research.

Observation:

• A rare case of an epidermoid cyst on the upper chest presented with unusual histologic features.
• The cyst exhibited structures resembling eccrine ducts and acrosyringia within the horny layer.
• Immunohistochemical staining revealed carcinoembryonic antigen (CEA) expression in these ductal structures.

Findings:

• The histologic findings suggest a potential origin of this epidermoid cyst from eccrine duct structures.
• The presence of CEA further supports the eccrine differentiation within the cyst.
• This case expands the known locations for epidermoid cysts with eccrine differentiation.

Implications:

• Epidermoid cysts derived from eccrine ducts may not be limited to the extremities.
• This case highlights the diverse differentiation capabilities of epidermoid cysts.
• Further research may elucidate the specific pathways involved in eccrine differentiation of epidermoid cysts on the torso.