This action was brought by appellant Joanne Stauffer who seeks damages for personal injuries which resulted from excessive exposure to radiation following a radical mastectomy. By order of June 23, 1987, the lower court granted summary judgment in favor of appellee Dr. Ebersole1 finding that, as a matter of law, appellant’s suit was not timely filed as she knew or had reason to know of her injury more than two years before suit was commenced. The sole issue presented by this appeal is whether the lower court erred in finding that appellant’s claim was barred by the applicable statute of limitations.
Appellant initiated the instant suit in April, 1984, by writ of summons. A complaint was thereafter filed in which appellant alleged that in 1977, appellee had administered to her an overdose of radiation which years later resulted in severe injury to the nerves of her left arm and hand. Appellant further alleged that despite reasonable diligence, she did not discover the actual cause of her injury until May, 1982. Appellee filed a timely answer and new matter in which he raised the statute of limitations as a defense. After depositions were taken by each party, appellee filed a motion for summary judgment which was granted by the court on June 23, 1987. This appeal followed.
The facts of record are as follows. In January, 1975, appellant had a radical mastectomy performed on her left breast and two years later the cancer recurred. Following further surgery, appellant was sent to appellee for radiation therapy which was administered from late 1977 through early 1978. In late 1978 appellant began to experience numbness in the tips of some of the fingers on her left hand. At that time she spoke with her parent’s treating physician about the symptoms and he related that they possibly were caused by scar tissue. However, the physician, Dr. Smith, did not correlate the scar tissue to appellant’s radiation treatment. Appellant’s cancer also occurred in her right breast in 1979 and when she was admitted for *309surgery, she complained of the numbness in her fingers to her doctor. However, no tests were conducted and no diagnosis was made.
By 1980 appellant’s numbness became acute, spreading from the tips of some of the fingers to her left hand and arm, accompanied by severe pain. Appellant sought the treatment of Dr. Medinger who conducted a battery of tests and in 1982 determined that the symptoms were caused by calcium deposits (fibrosis) forming in appellant’s neck which pressed on the nerve endings leading to her left arm and hand. Dr. Medinger determined that the calcium deposits were the result of excessive exposure to the radiation administered to appellant in 1977. Appellant has now lost the use of her left and dominant hand and arm.
An action to recover damages for personal injuries is governed by a two-year statute of limitations. 42 Pa.C.S.A. § 5524(2). Thus, a plaintiff must commence an action within two years from the time he or she suffers an injury. However, when an injury is not readily discernible, the discovery rule, as discussed below, applies. Where this judicial doctrine is applied, the statute of limitations is tolled and does not begin to run until the plaintiff has discovered, or in the exercise of reasonable diligence should have discovered, the injury. See Groover v. Riddle Memorial Hospital, 357 Pa.Super. 420, 516 A.2d 53 (1986), allocatur den. 515 Pa. 600, 528 A.2d 957 (1987).
The discovery rule exception arises from the inability of the plaintiff, despite the exercise of diligence, to determine the existence of the injury or its cause. See Larthey by Larthey v. Bland, 367 Pa.Super. 67, 532 A.2d 456 (1987), allocatur den. sub nom. Larthey v. Bland, 518 Pa. 656, 544 A.2d 1343 (1988). The statute of limitations begins to run when a plaintiff knows, or reasonably should know that an injury has occurred and that the injury was caused by another party’s conduct. Citsay v. Reich, 380 Pa.Super. 366, 370, 551 A.2d 1096, 1098 (1988); Larthey, supra; Cathcart v. Keene Industrial Insulation, 324 Pa.Super. 123, 471 A.2d 493 (1984). See also Levenson v. Souser, 384 *310Pa.Super. 132, 557 A.2d 1081 (1989) (en banc) (explicating history and current status of discovery rule in Pennsylvania).
Appellant maintains that the lower court’s grant of summary judgment was unreasonable in her case because she was not expected, under the discovery rule, to bring suit when her symptoms first appeared but rather when her injury was diagnosed. In support of this allegation, appellant cites Trieschock v. Owens Corning Fiberglas Company, 354 Pa.Super. 263, 511 A.2d 863 (1986), allocatur den., 514 Pa. 619, 521 A.2d 933 (1987). In that case, as part of a routine medical screening conducted by his employer, appellant was told by the company doctor that he was suspected of having asbestosis in March, 1982. On April 8, 1982, the diagnosis was confirmed by a specialist and appellant filed suit on April 6, 1984. If the statutory two year period period started to run from the diagnosis of the first physician in March, 1982, even though based on mere suspicion, appellant’s suit was not timely filed. If the statute of limitations began with notification by the specialist of the cause of appellant’s symptoms, the case was initiated in time. The Trieschock court opined:
As a general principle, the statute of limitations begins to run in a tort case when the cause of action accrues. When the cause of action accrues is, of course, quite apparent when a collision forms the grounds for the suit. But when the injury is, as here, due to a “creeping disease,” developing for years without symptoms after the exposure to the causative agents, that date is simply not ascertainable____ The question before us then is whether the fact that appellant was told that asbestos was suspected would establish, as a matter of law, that appellant knew, or should have known that he had asbestosis, an “injury.”
354 Pa.Super. at 265-66, 511 A.2d at 865 (citations omitted).
A plaintiff in a creeping disease case should not be required to have greater knowledge than his physicians about his medical condition. If those physicians are not *311reasonably certain as to his diagnosis, then he certainly cannot be bound to have the knowledge necessary to start the statute of limitations running.
354 Pa.Super. at 268, 511 A.2d at 866. While Trieschock concerns the application of the discovery rule to a “creeping disease,” we find it to be instructive to this case because appellant’s injury began with minor symptoms which became progressively worse over a period of time.
The lower court found that although appellant’s testimony was confusing, vague, and not responsive to the questions asked, it revealed that she knew of her injury in 1979 when she questioned Dr. Smith, her parent’s physician, about the numbness in her fingers and he told her that her problems were caused by scar tissue. The question before us then is whether the fact that, without benefit of a medical workup, appellant was told her problems possibly were caused by scar tissue, established as a matter of law that appellant knew or should have known she had an injury caused by appellee.
A finding that appellant knew or reasonably should have known the cause of her symptoms when she spoke to Dr. Smith would lead to a result inconsistent with that in Trieschock. Dr. Smith’s diagnosis was done without the benefit of exact medical knowledge. Dr. Smith neither performed tests nor examined the appellant. His opinion was based on his knowledge of appellant’s medical history and what she described as symptoms. Thus, Dr. Smith’s opinion was a mere suspicion absent any testing and did not allude to a proximate cause of appellant’s symptoms. To put upon appellant the duty of knowing the nature of her ailment and its relation to her prior treatment before it is ascertained with a degree of certainty by the medical profession is a great burden to impose upon her. The information conveyed to appellant by Dr. Smith may well have been too imprecise to start the running of the statute of limitations against a lay person whose knowledge certainly is not as expert as that of a member of the medical profession. *312Our inquiry, however, does not end here. While Dr. Smith’s speculative diagnosis may have been insufficient to start the running of the statute of limitations, it activated a duty on appellant’s part to determine with due diligence whether the radiation treatments did in fact cause her injury. “The absence of such a duty would mean that a potential plaintiff with a tentative diagnosis could wait indefinitely before acting to confirm it.” Trieschock, 354 Pa.Super. at 268, 511 A.2d at 866.
Dr. Smith gave his tentative diagnosis to appellant regarding the numbness in her fingers in 1979. Shortly thereafter appellant underwent surgery for the removal of her right breast. While giving information to her doctor in relation to that surgery, appellant told him of the numbness she experienced in fingers of her left hand. Dr. Patterson noted her symptoms on his records but conducted no tests to determine their cause. Subsequent to cancer surgery, appellant was in need of further treatment. It was suggested by some doctors that she undergo chemotherapy while others recommended radiation. Because she was confused as to which treatment would be better for her, appellant consulted Dr. Medinger in 1980. By this time the numbness in appellant’s hand was acute and accompanied by pain. Dr. Medinger did a complete workup on appellant and referred her to several specialists. In 1982 appellant’s symptoms were diagnosed as fibrosis or calcium deposits in her neck which press on the nerves leading to her left arm and hand. It wasn't until then that medical experts determined appellant’s injuries were caused by overexposure to radiation appellant had received while under treatment by Dr. Ebersole in 1977.
However, there are sufficient factual circumstances presented to us in this case which give rise to the question of whether appellant exercised due diligence in finding out the cause of the numbness in her hand. The information that she received from Dr. Smith concerning this physical condition in 1979 and her complaints with regard to this same physical condition to the doctors who performed can*313cer surgery on her, raised the issue of the presence or absence of due diligence on the appellant’s part in determining the cause of her hand problem. Thus, whether plaintiff’s lawsuit was brought within the statute of limitations is a question for the jury to determine based on the facts as developed at trial. Viewing the evidence in a light most favorable to appellant as the non-moving party, and drawing all reasonable inferences in her favor, we conclude that summary judgment was improperly granted. Order of the lower court granting appellee’s motion for summary judgment reversed and case remanded for further proceedings in accordance with the foregoing. Jurisdiction relinquished.
BECK, J., files a dissenting opinion.. Appellant discontinued suit as to the other named defendants.