American Tower ( AMT) says it has found irregularities with some of its stock-option grants.

The Boston-based wireless-antenna network operator said Friday that an internal review had uncovered dates of stock-option grants that "likely differ from the recorded grant dates of such awards."

American Tower ranks among dozens of companies, including Juniper ( JNPR), Broadcom ( BRCM) and UnitedHealth ( UNH), that have been caught up in a growing backdating scandal . Many of these companies are under scrutiny for grants that seemed to be timed to enhance the value of the stocks options held by executives and employees.

In May, American Tower said it had received notice that federal agencies were probing the company's option-grant history.

The company says it may need to "record additional noncash charges for stock-based compensation expense relating to these option grants." American Tower hasn't determined whether a restatement will be necessary, though it said any restatements won't have a material impact on cash flow from operations and are not expected to change "historical revenues or nonoption related operating expenses," the company said in a press release Friday.

American Tower expects to discuss the options discovery during a conference call Aug. 7.

Shares of the company were down a dime to $31.54 in early trading Friday.