          United States Court of Appeals
                     For the First Circuit

No. 09-2528

      MARISOL RODRÍGUEZ-DÍAZ; JOSÉ RAFAEL FERRERAS-DURAN;
            CONJUGAL PARTNERSHIP FERRERAS-RODRÍGUEZ,

                     Plaintiffs, Appellants,

                               v.

      SEGUROS TRIPLE-S, INC.; JAVIER J. RODRÍGUEZ-BECERRA;
               CONJUGAL PARTNERSHIP RODRÍGUEZ-DOE,

                     Defendants, Appellees.


          APPEAL FROM THE UNITED STATES DISTRICT COURT

                 FOR THE DISTRICT OF PUERTO RICO

         [Hon. José Antonio Fusté,    U.S. District Judge]


                             Before

                  Torruella, Boudin and Lipez,

                         Circuit Judges.


     Jorge Miguel Suro Ballester for appellants.
     Benjamín Morales-del Valle with whom Jaime E. Morales Morales
and Morales-Morales Law Offices were on brief for appellees.




                        February 23, 2011
           BOUDIN, Circuit Judge.          This is an appeal by Marisol

Rodríguez-Díaz and her husband José Rafael Ferreras-Durán from a

decision granting summary judgment to Dr. Javier J. Rodríguez-

Becerra ("Dr. Rodríguez") and his insurer Seguros Triple-S, Inc. in

a medical malpractice action brought under Article 1802 of the

Puerto Rico Civil Code, P.R. Laws Ann. tit. 31, § 5141 (1990).             We

recount the facts in the light most favorable to the plaintiffs as

the non-moving parties.       Statchen v. Palmer, 623 F.3d 15, 16 (1st

Cir. 2010).

           In early 2007, Rodríguez-Díaz, a forty-five-year-old

woman then resident in Puerto Rico with a personal and family

history of thyroid cancer, felt a lesion in her left parotid gland,

which is one of the salivary glands.            Her treating physician, Dr.

José   Arsuaga,    referred   her   to   Hato    Rey   Pathology   Associates

("HRPA") to undergo a fine needle aspiration biopsy of her left

parotid gland.     Dr. Rodríguez, a physician at HRPA, performed the

biopsy on March 1 and issued a cytology report on March 6.

           Dr. Rodríguez's report provided a pathologic diagnosis of

pleomorphic adenoma, which is a benign tumor of the salivary

glands.   That diagnosis--and Dr. Rodríguez's failure to conduct a

"differential diagnosis"--is the basis of this suit.            Differential

diagnosis is a standard technique for "the determination of which

of two or more diseases with similar symptoms is the one from which

the    patient    is   suffering,   by     a    systematic   comparison   and


                                     -2-
contrasting    of    the     clinical      findings."         Stedman's     Medical

Dictionary 492 (27th ed. 2000); see also Baker v. Dalkon Shield

Claimants Trust, 156 F.3d 248, 252-53 (1st Cir. 1998).

              Dr. Arsuaga told Rodríguez-Díaz of Dr. Rodríguez's

diagnosis on March 30, 2007, and recommended surgical removal of

the tumor--the standard treatment for pleomorphic adenoma--but said

that there was no urgency.                Rodríguez-Díaz later scheduled a

consultation    with      Dr.    Thomas   Shellenberger,      a   head    and   neck

surgical oncologist at the M.D. Anderson Cancer Center in Orlando,

Florida, and requested her biopsy slides from HRPA to take to Dr.

Shellenberger.      Under HRPA policy, this request required a review

of the slides by another HRPA physician.

           Dr. Víctor J. Carlo-Chévere ("Dr. Carlo"), one of Dr.

Rodríguez's colleagues at HRPA, reviewed Rodríguez-Díaz's slides

and diagnosis.       Dr. Carlo conducted a differential diagnosis,

included mucoepidermoid carcinoma--a malignant tumor--as one of the

possibilities, and therefore conducted a mucicarmine stain (which

Dr.   Rodríguez     had    not   done)    to    check   for   mucin,     indicating

mucoepidermoid carcinoma.          Dr. Carlo produced an amended cytology

report that changed Rodríguez-Díaz's pathologic diagnosis from

pleomorphic adenoma to low grade mucoepidermoid carcinoma.

           On July 18, 2007, Rodríguez-Díaz picked up the slides and

Dr. Carlo's amended cytology report with the revised diagnosis of

a malignant tumor.         She alleges that when she read Dr. Carlo's


                                          -3-
report, realized Dr. Rodríguez's report was not correct, and

learned she had cancer, she and her husband were shocked and their

lives fell apart.         Now mistrusting Puerto Rico physicians, they

resorted at great expense to health care in the continental United

States, which their health insurer refused to cover.

           On    August    29,   2007,   Dr.    Shellenberger     successfully

operated   on    Rodríguez-Díaz,    surgically      removing    the    malignant

tumor.   The attendant pathology confirmed the revised diagnosis of

a malignant tumor.     Within the year, on August 8, 2008, Rodríguez-

Díaz and her husband brought this malpractice action in federal

district court in Puerto Rico against Dr. Rodríguez and his medical

insurer.    Having    become     residents     of   Florida,    they    premised

jurisdiction on diversity.        Their claim was that Dr. Rodríguez had

been negligent in failing to conduct a differential diagnosis.

           During discovery, Dr. Rodríguez stated that he had not

conducted a differential diagnosis because the evidence that he

discerned in studying the biopsy slide and described in his report

(specifically,     myxoid stroma, epithelioid cells, and plasmacytoid

cells) persuaded him that Rodríguez-Díaz suffered from a benign

tumor,   making    unnecessary     any    differential     diagnosis.       The

defendants thereafter moved for summary judgment. Their supporting

evidence went considerably beyond Dr. Rodríguez's explanation.

           The    defense    offered     by    expert   witness   report    and

deposition testimony that the treatment for pleomorphic adenoma--


                                       -4-
which can become malignant--and low grade mucoepidermoid carcinoma

are the same; that Rodríguez-Díaz had received the appropriate

treatment in sufficient time; that an Orlando specialist had in

July 2007 reviewed the same slides and made no diagnosis of

malignancy; and that no definitive diagnosis could be made until

surgery.

            In opposition, Rodríguez-Díaz offered no expert testimony

on the standard of care.     She relied primarily on the failure of

Dr. Rodríguez to conduct a differential diagnosis and thus to

consider low grade mucoepidermoid carcinoma as an alternative to

pleomorphic adenoma; on Dr. Carlo's use of the technique and the

mucicarmine stain test in an attempt to exclude this alternative;

and on Dr. Carlo's correct diagnosis and its confirmation after

surgery.    Rodríguez-Díaz made no claim of physical harm from the

delay in surgery but did claim emotional distress and increased

expenses due to her concern about medical care in Puerto Rico.

            On September 22, 2009, the district court granted the

defendants' motion for summary judgment, ruling that the plaintiffs

could not establish a prima facie claim of medical malpractice

under Article 1802 because they had not offered expert evidence

establishing the relevant standard of care.        The plaintiffs now

appeal.    Our review is de novo.    Great Clips, Inc. v. Hair Cuttery

of Greater Bos., L.L.C., 591 F.3d 32, 35 (1st Cir. 2010).




                                    -5-
           This being a diversity suit, the substantive law of

Puerto Rico governs.   Erie R.R. Co. v. Tompkins, 304 U.S. 64, 78

(1938).   Under Puerto Rico law, the applicable rule of decision in

a medical malpractice action is fault-based, Martínez-Serrano v.

Quality Health Servs. of P.R., Inc., 568 F.3d 278, 285 (1st Cir.

2009); Article 1802 provides in pertinent part that "[a] person who

by an act or omission causes damage to another through fault or

negligence shall be obliged to repair the damage so done."      P.R.

Laws Ann. tit. 31, § 5141.

           To show medical malpractice, a plaintiff must establish

that the care afforded did not meet "the professional requirements

generally acknowledged by the medical profession."   Santiago Otero

v. Méndez, 1994 P.R.-Eng. 909,224, 135 P.R. Dec. 540 (1994); see

also Pagés-Ramírez v. Ramírez-González, 605 F.3d 109, 113 (1st Cir.

2010) (listing the elements). This, in turn, "[a]lmost invariably"

requires the plaintiff to introduce expert testimony. Cruz-Vázquez

v. Mennonite Gen. Hosp., Inc., 613 F.3d 54, 56 (1st Cir. 2010).

Under Puerto Rico law, to make out a prima facie case of physician

negligence:

           Plaintiff must establish, through expert
           evidence, the degree of care and scientific
           knowledge required by the profession in the
           treatment of a specific type of patient.

Rodríguez Crespo v. Hernández, 21 P.R. Offic. Trans. 637, 647




                                -6-
(1988).1
           Despite such broad statements, the jury's own common

sense could occasionally close the gap and establish that the care

afforded did not meet minimal standards.                See Rolon-Alvarado v.

Municipality of San Juan, 1 F.3d 74, 79 (1st Cir. 1993) (offering

examples of possible exceptions); W. Keeton et al., Prosser and

Keeton on the Law of Torts § 32, at 189 (5th ed. 1984) (same).               And

the   expert     evidence,    if   required,    might    come   not   from   the

plaintiff's expert but rather from, say, the defense expert or

admissions by the defendant doctor.             See Chizmadia v. Smiley's

Point Clinic, 873 F.2d 1163, 1165 (8th Cir. 1989).                The present

case, however, fits neither of these possible exceptions.

           Differential diagnosis is a standard tool, but as to what

symptoms   and    in   what   conditions    a   differential     diagnosis    is

required for proper medical care, no lay jury would be likely to

know on its own.       Rolon-Alvarado, 1 F.3d at 79.        The fact that Dr.

Carlo conducted a differential diagnosis in this case, and that its

application led to the correct diagnosis, does not show that

failing to use it was negligent.         There is no indication that Dr.

Carlo or another physician testifying as an expert was prepared to

say otherwise.



      1
      See also Pagés-Ramírez, 605 F.3d at 113; Martínez-Serrano,
568 F.3d at 285; Rojas-Ithier v. Sociedad Espanola de Auxilio Mutuo
y Beneficiencia de P.R., 394 F.3d 40, 43 (1st Cir. 2005); Cortés-
Irizarry v. Corporación Insular de Seguros, 111 F.3d 184, 190 (1st
Cir. 1997); Lama v. Borras, 16 F.3d 473, 478 (1st Cir. 1994).

                                      -7-
               In the present case, counsel for Rodríguez-Díaz was asked

at oral argument why no expert was presented for the plaintiffs; he

answered, quite plausibly, that he made every effort to find one

but was unsuccessful. This hardly disproves the plaintiffs' claim:

doctors, especially in tightknit communities, may be hesitant to

accuse each other; pathology is a specialized field which could

further narrow the supply of experts; and although experts can

usually be found somewhere at some price, the lack of physical

injury here likely limited what the plaintiffs could promise to

pay.

               Plaintiffs' counsel made an admirable effort to do his

own medical research.           He cited both in the district court and on

this       appeal    a   2002   study   in   a   medical   periodical      for   the

proposition that low grade carcinoma is one of the differential

diagnoses of pleomorphic adenoma.2               Yet he has not argued directly

that this article, standing by itself, would allow the jury to

conclude that every pleomorphic adenoma requires for proper medical

treatment a differential diagnosis or the mucicarmine stain test.

               We think that the implicit concession is warranted.               The

article      is     highly   technical--even      to   understand   much    of   the


       2
      Stanley, Selected Problems in Fine Needle Aspiration of Head
and Neck Masses, 15 Modern Pathology 342 (2002). He also cited
literature to support the view that, where mucin is present, a
definitive judgment should be deferred pending further testing, see
Jacobs, Low Grade Mucoepidermoid Carcinoma ex Pleomorphic Adenoma,
38 Acta Cytologica 93 (1994), but such literature is of no help in
establishing when proper care requires the test to identify mucin.

                                         -8-
terminology would require a medical dictionary and probably some

science--and nowhere does it contain a flat statement that in every

case    where   pleomorphic   adenoma      is   diagnosed    a   differential

diagnosis or the mucicarmine stain test is required.             To say that

a set of symptoms can encompass several different conditions says

nothing about the precise mix in the case at hand, let alone what

other factors might suggest about the need for differentiation.

            One can easily conjecture reasons why differentiating

might matter; the most obvious is the relative urgency of the

surgery. The surgery itself would also differ, but it appears from

testimony that this would likely be determined definitively during

the preliminary steps of the surgery itself rather than by the

stain test.     Absent an expert witness, however, it would be hard

for the jury to know anything about relative urgency or any need

for    differentiation   on   some   other      basis--let   alone   how   the

patient's specific symptoms or the slide results in this case might

bear upon the question.

            We have, as required in a summary judgment case, drawn

reasonable inferences in the favor of the plaintiffs as the parties

resisting the judgment, Faiola v. APCO Graphics, Inc., 629 F.3d 43,

45 (1st Cir. 2010), but the outcome does not turn on evaluating the

evidence under a reasonable jury standard. Rather, the appeal fails

because there is a legal rule requiring expert testimony in a case




                                     -9-
of this character, and possible exceptions to the rule have not been

shown to apply.

          The judgment of the district court is affirmed. Each side

is to bear its own costs on the appeal.

          It is so ordered.




                               -10-
