First of all congratulations on such a good rank. The Directorate of Medical Education ( DME), Chennai takes the authority in admission to various PG medical courses in  Tamilnadu. Candidates those who have successfully submitted the application form will be eligible and included in the state rank list. The application for the same is expected to start from the third week of March. In Tamilnadu 50% of the seats are reserved for State quota and rest 50% All India Quota.

Since you have a decent All India Rank, your state rank will reduce a bit,

If you have fulfilled the following eligibility criteria:-

1) citizen of India and have passed the MBBS degree from a college recognised by Medical Council of India.

2) Candidates should have passed MBBS from a college of Tamilnadu, if not they must have a domicile certificate of nativity.

3) Completed rotatory internship from a Tamilnadu on or before 31st March.

See this dermatology is usually given to the toppers. You might or might not get this field.

All the best.

For more information you may follow the link,:-

https://www.google.com/amp/s/medicine.careers360.com/articles/tamil-nadu-pg-medical-admission/amp