Damp ceiling below ventilation tile

[Geoff52]

A damp patch has appeared on my bathroom ceiling below a roof ventilation tile. I have been onto to the roof and the ventilation tile and surrounding tiles look ok. There is an extractor fan in the ceiling not far from the damp patch. Thanks for looking, hope someone can help.

[tucny]

You say there is a damp patch. What does it look like? Take a photo if possible.

[Geoff52]

Thanks for reply. Patch is dark but lighter in centre and about 12" across. I said it was a damp patch but it doesn't feel damp. It appears to be getting worse even though we have had no rain! I'll try and sort out photo.

[rosebery]

Condensation?

Cheers