Just about the time you think they may be running out of topics for those issue- oriented TV movies, just when you think the format has been worn threadbare, there comes "An Early Frost."

In its timing and execution, it may be the perfect issue-of-the week TV film. Near perfect, anyway.

"An Early Frost," an enigmatically titled CBS offering, tells the story of a young attorney who contracts AIDS and then has to endure the medical, social and familial consequences.

Even though the movie has been two years in various phases of production, it comes at the right time, at a point where interest in AIDS seems to be moving past concern and on to hysteria, rising to the top of pollsters' lists of most-dreaded diseases.

It is the first dramatic movie-length treatment of AIDS on television. And for what it is and what it tries to do, "An Early Frost" is a neatly executed little film. Not to say that it will solve the AIDS problem overnight or calm America's collective fears, but it serves as a tidy dramatic primer. What more can be asked of such a show?

Aidan Quinn stars as the lawyer who's enjoying a soaring career when he's diagnosed as suffering from AIDS. Ben Gazzara is his father, a very physical man given to 5 a.m. workouts, whose first impulse upon hearing of his son's illness -- and his homosexuality -- is to smack him. Gena Rowlands is his mother, steadfast and understanding from beginning to end, ever the peacemaker. Sylvia Sidney plays the grandmother, amply supplied with sage comments onscreen and off.

There are other characters too -- the gay roommate, who worries that his infidelity may have introduced Quinn's character to AIDS, and the sister, expecting a child, who won't let her stricken brother come near her.

In the pat ending, all the loose ends of personal conflict are wrapped up with hugs all around, and at the final fade, everyone's conscience is clear. But there is no glossing over Quinn's fate.

NBC is treating the film as one dealing with a vital public health issue. In connection with the program, the network has conducted a massive informational mailing to some 200,000 health, education and social organizations. Following the film (and local news programs) Tom Brokaw will host an NBC News special dealing with the disease, entitled "AIDS Fear/AIDS Fact." It will be carried by Channels 2 and 4 at 11:30 p.m.

Production of "An Early Frost" also evoked strong reactions from some of its players, ranging from the newcomer Quinn ("Desperately Seeking Susan," "The Mission"), who gave part of his fee to AIDS research, to the veteran Sidney, who helped put the show in perspective.

Quinn expressed strong sympathy with AIDS patients, putting down fears that those exposed to AIDS victims might catch it. "The real concern around AIDS patients," he said, "is that you might give them something because their immune system is so low. I think the kissing and school-children controversies are ridiculous," Quinn said flatly, acknowledging that he has no children of his own. "It's bad enough that people have AIDS. Why do we have to treat them as pariahs, as lepers?"

Quinn said he donated money to a West Coast-based AIDS group that had assisted him in doing research for his part. "They helped me a lot," Quinn said. "I wanted to give something back."

Director John Erman, who noted that he had not been so touched by a script since he directed (and won an Emmy for) "Who Will Love My Children?", also said he was moved during the research phase of production, in which he and others were introduced to AIDS patients who were living out their final days.

"Aidan and I visited a member of the creativ community who was suffering from AIDS," Erman recalled. "He died the night we saw him."

During the two years the film was in progress, numerous script changes had to be made to keep up with developments on the medical front. "The information being given by the doctors in the film was being constantly updated as shooting went along," said Erman. Arrangements have been made to make further changes possible right up to airtime.

Aidan recalled three AIDS victims he had met during the filming who will not see the final product. And Sidney said three of her acquaintances have died of AIDS in the past year.

But perhaps more importantly, Sidney cared for her son, Jacob Adler, as he died of Lou Gehrig's disease. Her experience gave her a wider view of what "An Early Frost" is all about.

"The film is not about AIDS or homosexuals," she said. "The point is how you handle a difficult situation in your personal relationshps (regardless of the disease or the problem). Forty years ago you didn't mention cancer. When I was a girl you didn't mention TB. What the film really is about is the education of people (about dread, complex diseases). And it's about supporting victims during the most difficult time of their lives."