Lymphoepithelioma-like Carcinoma (LELC)

Epidemiology and Etiology:

• Rare
• M:F = 2:1
• Bimodal peak at 14 and 48y
• EBV may be associated (47%)

Common sites:

• Anterior mediastinum
• Mets:
• Liver
• Lung
• Lymph node
• Bone

Gross features:

• Solid
• Yellow-white
• Areas of necrosis
• Incompletely encapsulated
• Extension to contiguous structures is usual

Histologic features:

• syncytial growth of undifferentiated carcinoma cells
• nests or anastomosing cords
• accompanying lymphoplasmacytic stroma similar to undifferentiated CA of the nasopharynx
• intimately admixed with tumour cells as well 
• tumour cells:
• large vesicular nuclei with open chromatin
• one or more distinct eosinophilic nucleoli
• uneven crowding of nuclei, may overlap
• indistinct cytoplasmic membranes
• frequent mitoses often
• foci of tumour necrosis often
• may see:
• germinal centres
• eosinophils
• granulomas

Immunophenotype:

Marker:	Sensitivity:	Specificity:
AE1
AE3 (neg)
CK7 (neg)
CK20 (neg)
CD5 (focal or neg)
BCL-2	Commonly
CD3 (majority of lymphoid cells)
CD5 (majority of lymphoid cells)
CD1a (neg)
CD99 (neg)
TdT (neg)
CD20 (smaller numbers of lymphoid cells)
No light chain restriction

Molecular features:

Other features:

• SVC syndrome when advanced
• no association with myasthenia gravis or other paraneoplastic syndromes
• poor prognosis

References:

•  WHO book 2004