The Doctors Company (TDC) is the largest physician-owned professional liability insurance company in the United States and insures more than 1,100 pathologists who practice in every state. Therefore, its claims should be representative of problems occurring in many pathology practices. In the process of reviewing pathology claims the author observed that the misdiagnosis of melanoma was a repetitive problem. This impression was reinforced by a computer search of all claims reported to TDC from 1990 through 2001, which revealed that 8.6% of pathology claims and 14.2% of dermatology claims involved the key words “skin cancer” and/or “melanoma”. This finding led to a detailed analysis of individual pathology claims reported from 1995 through 2001.
The author reviewed 218 surgical pathology and fine needle aspiration biopsy claims reported to The Doctors Company from 1995 through 1997. 11% of these claims (#23) involved the misdiagnosis of melanoma; 70% were false negative diagnoses. Melanoma claims were second only to claims involving breast biopsy. Subsequently an additional 144 surgical pathology and cytology claims from 1998 through 2001 were reviewed. 16% of these claims (#23) involved misdiagnosed melanoma.
A Melanoma Risk Management Panel of expert dermatopathologists was convened in April 2002 at The Doctors Company home office in Napa, California. The purpose was to devise useful strategies that pathologists and dermatologists could use in their practices to reduce the risk of diagnostic error and/or patient mismanagement when dealing with melanocytic lesions – focusing on the recurrent “problem areas” identified by the author in the 23 melanoma claims reviewed from 1998 through 2001.
Ten recurrent problems were identified:
The misdiagnosis of melanoma continues to be a major cause of malpractice claims filed against pathologists and dermatologists. While specific problem lesions were identified (nevoid melanoma, Spitz nevus, desmoplastic melanoma, and dysplastic nevus) many claims involve "classic" melanoma misdiagnosed as melanocytic nevus without an identifiable explanation. However, the reproducible diagnosis of melanoma appears to be a problem even for experienced dermatopathologists. A panel of 11 experts reviewing 37 classic melanocytic tumors agreed unanimously on the diagnosis of benign versus malignant on only 35% of cases1,2. When 6 university pathologists reviewed 94 melanoma slides, their agreement was good for Breslow thickness, moderate for growth phase, and fair for Clark level3. A discussion of the ten problem areas identified by the panel follows. The recommended guidelines are an attempt to identify strategies that may be helpful in reducing the risk of diagnostic error and enhancing patient management. They are not rules. Only the physician who is knowledgeable of the circumstances prevailing in each individual situation can make the ultimate decision regarding their appropriate application.
Excisional biopsy is recommended for all melanocytic lesions because a partial biopsy may result in a partial diagnosis, which may be a misdiagnosis. Nevertheless, despite admonitions to completely excise melanocytic lesions, primary care clinicians and dermatologists continue to perform punch and shave biopsies - and this practice appears to be increasing under “managed care”. These “partial biopsies” may sample non-diagnostic areas of a melanoma or an associated benign nevus; they don't include the deepest portion of the lesion or the diagnostically helpful radial growth phase; and unlike excisional biopsy specimens there is a residual lesion that may recur and/or metastasize.
Punch and shave biopsies are often driven by cost considerations: scalpels cost more than razor blades, sutures are expensive, and a return visit is often required if a lesion is completely removed and sutured. However, these “savings” are trivial compared with the cost of a malpractice claim. If referring physicians continue to send partial biopsies, it is important for the pathologist to know the lesional diameter on the patient since this allows an estimate of the extent to which the biopsy sampled the lesion. Pathologists should encourage referring physicians to provide this information on all partial biopsies.
It is important to comment on the presence of nevocytes at margins – even for benign lesions AND to ask for re-excision of “problem” lesions (lesions showing some but not all the features required for a diagnosis of melanoma): a 0.5cm margin for superficial lesions and a 1.0cm margin for deep lesions is generally appropriate. A partial skin biopsy is analogous to a colonoscopic biopsy of a dysplastic adenomatous polyp, ie, if the biopsy is not excisional, the entire lesion is always removed. Suggested comments to add to the pathology report to encourage re-excision of partial biopsies include:
Such comments will often precipitate a phone call from the referring physician or a request for consultation, which is apt to assure appropriate follow-up.
When considering this diagnosis in an adult it is advisable and prudent to obtain consultation from an expert dermatopathologist. Spitz nevus is a high risk/low frequency diagnosis – analogous to soft tissue tumors or bone tumors. If a pathologist is not seeing Spitz nevi on a regular basis, and the patient is > 20 years old, the case should be sent to an expert. If Spitz nevi are being seen on a regular basis and the patient is > 20 years old, unless all of the typical diagnostic criteria are present send the case to an expert. All Spitz nevi should be completely excised – even if the patient is < 20 years old. Even experts may disagree on problematic or atypical Spitzoid lesions; when this occurs some referral centers may perform sentinel lymph node biopsy and in one published report metastatic cells were found in the sentinel node in 5 of 10 cases4.
Finally, pathologists should always issue written reports to document verbal consultations – particularly with dermatologists, since the melanocytic lesions they want an opinion on are apt to be from lesions they have clinical concern about. When we are asked to look at a slide and give an opinion, we are giving a consultation for which we can be held liable. Without a written report, the only record is the clinicians recollection of the conversation or a handwritten note made in the office record or chart, which is often incomplete or inaccurate.
1.) Ackerman A. Discordance among expert pathologists in diagnosis of melanocytic neoplasms. Hum Pathol. 1996;27:1115-16.
2.) Farmer ER, Gonin R, and Hanna MP. Discordance in the histopathologic diagnosis of melanoma and melanocytic nevi between expert pathologists. Hum Pathol. 1996; 27:528-31.
3.) McDermott NC, Hayes DP, Al-Sader MH, et al, and Leader MB. Identification of Vertical Growth Phase in Malignant Melanoma. Am J Clin Pathol. 1998;110:753-57.
4.) Lohmann C, Coit D, Brady M, et al. Sentinel Lymph Node Biopsy in Patients with Diagnostically Controversial Spitzoid Melanocytic Tumors. Am J Surg Pathol. 2002; 26(1):47-55.
The following references are recommended as a supplement to the panel discussion on Melanoma Risk Management. The list is not intended to be comprehensive.
Cochran AJ, Bailly C, Cook M et al: Recommendations for the reporting of tissues removed as part of the surgical treatment of cutaneous melanoma. Am J Clin Pathol. 1998;110:719-22.
Cochran A J, Bailly C, Paul E, et al “Melanocytic Tumors: a guide to diagnosis”; Philadelphia: Lippincott-Raven;1992.
LeBoit LE and Ming ME. Litigious Melanocytic Proliferations and How to Avoid Them. Path Case Reviews 1999;4(2):77-86.
Ring A, Tan MW. Melanoma claims: from overreaction to oversight. CAP Today (August); 2002:59-62.
Stevens G and Cocherell CJ. Avoiding Sampling Error in the Biopsy of Pigmented Lesions. Arch Dermatol. 1996 Nov;132(11):1380-82.
Troxel D. Diagnostic Errors in Surgical Pathology Uncovered by a Review of Malpractice Claims. Part IV. Melanoma. Int J of Surg Pathol 2001;9(1):61-63.
Xu X, Chu A, Pasha T, et al. Immunoprofile of MIFT, Tyrosinase, Melan-A, and MAGE-1 in HMB45-Negative Melanomas. Am J Surg Pathol 2002;26(1):82-87.
McNutt NS. Triggered Trap: Nevoid Malignant Melanoma. Semin in Diag Pathol. 1998;15(3):203-09.
Zembowicz A, McCusker M, Chiarelli C, et al. Morphological Analysis of Nevoid Melanoma: A Study of 20 Cases (with review of the literature). Am J of Dermatopathol. 2001;23(3):167-75.
Barnhill RL, Argenyi ZB, et al. Atypical Spitz nevi/tumors: Lack of consensus for diagnosis, discrimination from melanoma, and prediction of outcome. Hum Pathol. 1999;30(5):513-20.
Harvell J, Bastian B, and LeBoit P. Persistent (Recurrent) Spitz Nevi. Am J Surg Pathol. 2002;26(5):654-61.
LeBoit P. “Safe” Spitz and Its Alternatives. Pediatr Dermatol 2002;19(2):163-65.
Orchard DC, Dowling JP, Kelly JW. Spitz nevi misdiagnosed histologically as melanoma. Australian J. 1997;38(1):12-14.
Smith KJ, Barrett TL, Skelton HG, et al. Spindle Cell and Epithelioid Cell Nevi with Atypia and Metastasis (Malignant Spitz Nevus). Am J Surg Pathol. 1989;13(11):931-39.
Dysplastic (atypical) nevus:
Piepkorn, M. Whither the Atypical (Dysplastic) Spitz Nevus? Am J Clin Pathol. 2001;115:177-79.
Pozo L, Naase M, Cerio R, et al. Critical Analysis of Histologic Criteria for Grading Atypical (Dysplastic) Nevi. Am J Clin Pathol. 2001;115:194-204.
Cox et al. Extrafacial Lentigo Maligna: Analysis of 71 Cases and Comparison With Lentigo Maligna Melanoma of the Head and Neck. Br J Dermatol. 1998;139(3):439-44.
Flotte TJ and Mihm MC. Lentigo Maligna and Malignant Melanoma In Situ, Lentigo Maligna Type. Hum Pathol. 1999;30:533-36.
Jain S and Allen PW. Desmoplastic malignant melanoma and its variants. A study of 45 cases. Am J Surg Pathol. 1989;13(5):358-73.
Quinn MJ, Crotty KA, Thompson JF, et al. Desmoplastic and Desmoplastic Neurotropic Melanoma: experience with 280 patients. Cancer. 1998;83:1128-35.
Pitfalls in the Diagnosis of Malignant Melanoma
Findings of a Risk Management Panel Study
About the Author
David B. Troxel, M.D., is medical director of The Doctors Company. Dr. Troxel is clinical professor emeritus in the School of Public Health at the University of California at Berkeley. He is past president of the American Board of Pathology and the California Society of Pathologists.
Expert Panel Members:TDC Panel Participants:
ALISTAIR J. COCHRAN, MD RICHARD ANDERSON, MD
Professor of Pathology and Surgery Chairman, Board of Governors, TDC
Department of Pathology and Laboratory Medicine Medical Oncologist
UCLA School of Medicine
DAVID CHARLES, MD
SCOTT BINDER, MD Member, TDC Board of Governors
Chief, Dermatopathology Plastic Surgeon
Department of Pathology and Laboratory Medicine
UCLA School of Medicine MARK GORNEY, MD
Medical Director, TDC
PHILIP LeBOIT, MD Plastic Surgeon
Professor of Pathology and Dermatology
Director, Dermatopathology Services
University of California, San Francisco Expert Panel Chair:
CLIFTON WHITE, MD DAVID B.TROXEL, MD
Professor of Dermatology and Pathology Member, TDC Board of Governors
Director, Dermatopathology Pathologist
Oregon Health Sciences University
The guidelines suggested here are not rules, do not constitute legal advice, and do not ensure a successful outcome. The ultimate decision regarding the appropriateness of any treatment must be made by each healthcare provider in light of all circumstances prevailing in the individual situation and in accordance with the laws of the jurisdiction in which the care is rendered.