Plaintiff has been afflicted with scleroderma,1 a progressive, incurable disease, since the late 1930’s. She claims the right to receive disability benefits since 1971, the year in which she first applied for relief under the Social Security Act.2 It is perfectly clear that she was then — and indeed for many years had been — disabled within the meaning of the Act. However, because of the special earnings requirement of the statute,3 the Secretary determined that she must establish a period of disability commencing no later than December 31, 1950. Plaintiff’s failure to apply more promptly (which is attributed to lack of knowledge of her rights) thus not only limited the amount of her claim but also created unusually difficult problems of proof. The administrative law judge found in her favor, but the Appeals Council reversed.4 Our review of the entire record convinces us that the original determination of disability should be reinstated.
The Secretary has advanced two primary bases to support the decision of the Appeals Council. First is that plaintiff failed to satisfy her burden of proving a disability. Second is that the decision rests upon certain items of evidence which we should accept as substantial. Before evaluating the bases for the Secretary’s action, we shall briefly describe the uncontradicted evidence supporting plaintiff’s claim. This evidence includes plaintiff’s testimony, which the administrative law judge *1095credited; medical records; affidavits of plaintiff, some of her former co-workers and a doctor; a letter from her treating physician; and medical treatises describing scleroderma and Raynaud’s phenomenon.
I.
Except for the dispute over the date when plaintiff’s affliction became disabling, the facts are essentially uncontroverted.
Plaintiff was born in 1914. She now resides in Cicero, Illinois, with her husband, whom she married in 1935. Plaintiff did not complete her first year of high school and, except for an unfinished typing course, had no vocational training. She has had three jobs: as an assembly line riveter for Chicago Flexible Shaft Co. from 1937 to 1946; as a material cutter for Sears Roebuck in 1952 and 1953; and on an assembly line for Western Electric from 1955 to 1958.5
Shortly after starting at Chicago Flexible Shaft, plaintiff’s fingers began to trouble her.6 They became ulcerous, increasingly stiff and difficult to manipulate, especially in cold weather. She sought medical advice, but the doctors were unable to diagnose her affliction. Plaintiff’s fellow employees assisted her at work, but ultimately the company informed her that she would have to leave because she was physically unable to do her job.7
While unemployed between 1946 and 1952, plaintiff did some light housework. But her fingers were irritated by tasks such as dishwashing, and occasionally her condition would “flare up.” When plaintiff started to work at Sears, she believed her condition had improved; however, she could work neither continuously nor effectively. She had difficulty grasping scissors and “worked at a much slower pace than the other girls.” Her illness caused her to leave Sears in 1953.
Plaintiff’s doctors continued to treat her, but still were unable to determine the cause of her difficulties. Her discomfort increased. When she was upset or exposed to the cold, her feet and hands became numb and pallid. She also developed painful swelling of her fingertips and tightness of the skin on her upper arms and chest. Nevertheless, in 1955 she went to work for Western Electric. Plaintiff’s first assignment was on the assembly line tightening screws. However, she was unable to use a screwdriver effectively and was soon transferred. Her next assignment required that she dip her hands, covered by cellophane, into an acetone solution. As a result, plaintiff’s fingers were *1096greatly irritated and her condition deteriorated.8 In March of 1957 she entered the University of Illinois Research and Educational Hospital, where her condition was diagnosed as Raynaud’s phenomenon.9
Plaintiff remained in the employ of Western Electric until January 10, 1958. She was finally discharged because she could not perform the required work satisfactorily. While at Western Electric she had a high absence rate, was in great pain when she worked and received a good deal of assistance from her co-workers. The administrative law judge concluded that “her attempts to work resulted from severe economic need.”
In 1960 plaintiff reentered the Research and Educational Hospital. Her condition was diagnosed as scleroderma accompanied by Raynaud’s phenomenon. Between 1960 and 1971 plaintiff was admitted to the hospital on five separate occasions. She complained of progressive hardening and tenseness of the skin on various parts of her body, difficulty in swallowing, increasing inability to move her fingers and wrist, ankle edema, weight loss, and an asymptomatic mass in her left breast. On some occasions plaintiff would state that certain of these symptoms gave her less trouble than in the past. Nevertheless, her general condition became progressively worse.
In 1971 plaintiff was examined and found to be asthenic, diaphoretic and cyanotic. One plus pitting edema was noted in the extremeties, and her hands evidenced demonstrable tapering and mild atrophy. Tests further revealed an infarction and occlusion of arteries. The final diagnosis was arteriosclerotic heart disease, scleroderma in remission and recurrent thromboembolism. Since scleroderma is progressive, fatal and without cure, it is doubtful that plaintiff’s condition will ever improve. She has undergone some surgery and, for the most part, is now confined to bed.
II.
The Secretary’s initial contention is that plaintiff failed to prove, as required by 42 U.S.C. § 423(d)(1)(A), that she: (A) suffered from a medically determinable physical impairment; and (B) by reason of this impairment was unable to engage in any substantial gainful activity. According to the Secretary, we therefore must affirm the decision of the Appeals Council. See Kirkland v. Weinberger, 480 F.2d 46, 49 (5th Cir. 1973).
A.
42 U.S.C. § 423(d)(3) provides that a “physical or mental impairment” is
an impairment that results from anatomical, physiological, or psychological abnormalities which are demonstrable by medically acceptable clinical and laboratory diagnostic techniques.
The purpose of this section is to make clear that statements by a claimant or mere conclusions of others as to the nature and extent of an impairment are in*1097sufficient. There must be acceptable medical evidence that such an impairment existed. S.Rep.No. 744, 90th Cong., 1st Sess. (1967), reprinted in 1967 U.S.Code Cong. & Admin.News. pp. 2834, 2882-2883; 20 C.F.R. §§ 404.1501(c) & 404.1523 (1973). The Secretary argues that there is no medical evidence establishing plaintiff’s suffering from scleroderma prior to 1951; therefore, plaintiff failed to prove a “physical impairment.”
Plaintiff was unable to produce the medical records of the three doctors who treated her during the late 1940’s and early 1950’s. She explained that her records had been destroyed in a flood, that two of the doctors had long since been deceased and that the third doctor could not be located. The administrative law judge himself made an unsuccessful effort to find the records of these doctors. Plaintiff, however, did submit the medical reports of the University of Illinois doctors who treated her after 1957. A 1957 report contains a diagnosis of Raynaud’s phenomenon; a 1960 report, scleroderma. She also submitted an affidavit of Dr. Adolph Rostenberg, Jr., who followed plaintiff’s condition “for many years.” Based upon his contact with plaintiff and the affidavits prepared by plaintiff's coworkers at Flexible Shaft, Dr. Rostenberg concluded: “[I]t appears to me that Mrs. Stark’s scleroderma was present in and from the late 1930’s.”
The Secretary offered no medical opinion contradicting Dr. Rostenberg’s. Compare Williams v. Finch, 440 F.2d 613, 615-616 (5th Cir. 1971). Furthermore, the medical authorities cited by plaintiff and the administrative law judge are consistent with this opinion. They establish that the onset of scleroderma is insidious and its progression slow; while its cutaneous manifestations may, on occasion, regress, the disease nevertheless follows its fatal course. Raynaud’s phenomenon, pain, ulcerations and increasing tightness of the skin are all associated with the disease in its initial, as well as subsequent, stages. Finally, the University of Illinois reports contained in the record are also consistent with this opinion.10
A medical opinion does not become unacceptable, for purposes of § 423(d)(3), simply because it is based upon a claimant’s symptomology, Bittel v. Richardson, 441 F.2d 1193 (3d Cir. 1971), or upon medical records and lay testimony. See Kyle v. Cohen, 449 F.2d 489 (4th Cir. 1971). It is also clear that a diagnosis of a claimant’s condition may properly be made even several years after the actual onset of the impairment. Berven v. Gardner, 414 F.2d 857, 861 (8th Cir. 1969); Murphy v. Gardner, 379 F.2d 1, 7 (8th Cir. 1967). We thus conclude that Dr. Rostenberg’s affidavit is predicated upon a “medically acceptable clinical diagnostic technique” and that, when considered in light of the entire record, it establishes the existence of a “physical impairment” prior to 1951.
B.
A claimant is “unable to engage in substantial gainful activity” only if he satisfies the requirement of 42 U.S.C. § 423(d)(2)(A).11 To meet *1098his burden under this section, a claimant must demonstrate that his impairment is so severe that he is no longer able to perform the kind of work in which he has been engaged. If that showing is made, the burden shifts to the Secretary to prove that there is available some other kind of “substantial gainful employment” which claimant is able to perform.12
Prior to 1951, plaintiff’s only job had involved working with her hands on an assembly line operation. If she established that her impairment was sufficiently severe to prevent her from continuing to work in that capacity on December 31, 1950, she met her burden and it was incumbent upon the Secretary to prove the availability of alternate employment. Since the record in this case is devoid of any such proof by the Secretary, he is necessarily contending that plaintiff's impairment was not sufficiently severe prior to December 31, 1950, to prevent her from working with her hands.
The uneontroverted medical, as well as lay, evidence before us clearly refutes such a contention. There is no cure for scleroderma. One medical authority, who was cited by the administrative law judge, concluded:
Patients with slowly progressive systemic sclerosis can lead productive and useful lives. The most important goal in therapy is to preserve function in and prevent injury to the hands. Vocational and/or climatic change may be indicated. Hand care must be stressed, including instructions for active and passive exercises to prevent flexion contracture. Early signs of local infection in fingertips must be treated immediately before they progress to large ulcerations.
C. Loeb, Textbook of Medicine 813 (13th ed. 1971). Under this medical evidence it is clear that, for a person who works only with his hands, scleroderma should be considered disabling before the disease reaches its most advanced and crippling stages.13
In 1950 plaintiff had already been afflicted with this progressive, insidious disease for over 10 years. At that time, according to the medical evidence in the record, the proper treatment of the disease required her to stop working with her hands in such a way as would irritate them. Unfortunately, her affliction was not properly diagnosed until 1960; she did not thereafter return to work. We have no doubt that a correct diagnosis in 1951 would have revealed the need to avoid work of the kind she had been performing. Since the record demonstrates beyond challenge that her activities as an assembly line worker resulted in severe irritation of her fingers, and since the “most important goal in therapy” of scleroderma is to “prevent injury to the hands,” we conclude that *1099on December 31, 1950, the disease made her “unable to do [her] previous work” within the meaning of § 423(d)(2)(A).
Under a purely literal reading of the statute, plaintiff was “able” to do work which could only aggravate a malignant, progressive illness. We do not believe, however, that Congress enacted a rule of law which imposes any such duty upon its intended beneficiaries.
III.
The Secretary’s second contention is based upon three items of evidence adverse to plaintiff’s claim: (1) certain medical records placed the onset of her illness in about 1954; (2) on her application for benefits she stated that she first became unable to work in 1958; and (3) she was employed after 1950. The Secretary argues that this evidence is substantial support for the determination of the Appeals Council; therefore, under our narrow scope of review,14 we must affirm.15 It is, however, our duty to appraise this evidence in light of the entire record and not merely to view it “in isolation.”16 When viewed in this manner the facts upon which the Appeals Council relied are not substantial.
A fair reading of the medical records of the University of Illinois Research and Educational Hospital belies the suggestion that the onset of scleroderma did not occur until 1954. Some of plaintiff’s complications were not noticed until 1954,17 but others, such as the ulcerations, which were a primary cause of her disability, clearly were. We have no doubt, as found by Dr. Rostenberg and the administrative law judge, that her scleroderma was present while she was employed at Chicago Flexible prior to 1946.
Nor do we regard the admission in plaintiff’s application as controlling. In her answer to the question when she became unable to work because of her disability, she stated: “Dec. not the first 1958.” This answer is ambiguous because it is not clear whether she meant that December, 1958, was “not the first” time she became unable to work, or that she could not remember the specific date when she left Western Electric, but it was “not the first of December.”18 We think the latter interpretation is the more reasonable, but nevertheless do not consider this admission critical. When plaintiff completed the application she knew she had worked at Western Electric in 1958 and, since she was not represented by counsel, was unaware of the earnings requirement that made it necessary for her to establish an earlier disability date. She simply stated the fact that she was not totally unable to work until 1958. That *1100statement added nothing of legal significance to the evidence that she had in fact been employed both at Sears and at Western Electric after December 31, 1950. See Cook v. Ribicoff, 202 F.Supp. 558, 559 (S.D.Tex.1962). The difficult issue in this case, which the admission in her application merely highlights, is whether that post-1950 employment constitutes substantial evidence of non-disability as of December 31, 1950.
Unquestionably the regulations provide a basis for concluding that plaintiff’s employment during the period in which she claims to have been disabled is disqualifying.19 But it is clear that each case must be decided on its own facts,20 and post-disability employment is not necessarily disqualifying in every case.21 The question is not simply answered by the fact of employment or the extent of her earnings. Rather, the answer turns on whether she was disabled within the meaning of the Act notwithstanding the fact that she actually did work.
The uncontroverted evidence demonstrates that plaintiff worked only because she desperately needed the money; was transferred from one department to another because of her condition; needed the assistance of her co-workers to perform; had a high absence rate; worked in great pain; received the criticism of her foreman, and was finally fired, because she could not satisfactorily perform her job without assistance. Of greatest significance is the medical evidence which indicates that, if her condition had been properly diagnosed, she almost certainly would have been advised to discontinue work which could only aggravate a progressive incurable disease. Although neither she nor her doctors was fully aware of the extent of her disability while she was struggling *1101to maintain her earnings because of her “severe economic need,” we think it is now apparent that, at all times after 1950, her affliction was sufficiently serious to be disabling within the meaning of the Act.
IV.
We recognize the force of the argument that, even though we differ with the Secretary’s appraisal of the evidence, we may not substitute our judgment for his as long as the evidence supporting the denial is substantial and that, in this case, it is not unreasonable to characterize plaintiff’s post-1950 employment as substantial. Normally proper procedure might dictate a remand to receive expert testimony directed specifically at the question whether, having the benefit of later known symptoms, medical opinion would regard plaintiff as having been physically unfit to perform the work which she actually did perform after 1950. For three reasons, however, we decline to pursue that route.
First, as already stated, the uncontradieted evidence now in the record provides an affirmative answer to that question; we may not qualify that answer by discounting the testimony of a witness whom the administrative law judge saw, heard and credited. Second, since the claim only involves the period since 1971, and since the cost to both parties of further evidentiary hearings, with the possibility of still another appeal, is so disproportionate to the amount at stake, there is good reason to bring the proceedings to an end as expeditiously as possible. And finally, in view of the impossibility of determining with complete accuracy the extent of plaintiff’s affliction over two decades ago, the settled policy of construing the statute favorably to the claimant22 leads us to the result that seems manifestly just under all the circumstances.23
We therefore reverse the decision below with instructions to enter -judgment for the plaintiff.
Reversed.