Diagnostic Histopathology of Tumors

Abstract

When a clinician asks you whether you checked for SS18 gene rearrangement in an otherwise typical biphasic synovial sarcoma, the correct response is, “No, it isn’t necessary”; otherwise we will unwittingly undermine our own profession. —C. D. M. Fletcher, preface to Diagnostic Histopathology of Tumors, 5th edition Six years have elapsed since the previous edition of Fletcher’s Diagnostic Histopathology of Tumors was published. Its newest edition seeks to retain (or attain) a place on the crowded shelves of those among us who seek assistance in practicing the classic art and the changing science of surgical pathology. The book preaches pragmatism, and this philosophy is exemplified by the foregoing advice regarding the potentially gratuitous, if possibly gratifying, test for synovial sarcoma. The attention of Diagnostic Histopathology of Tumors spans from the pedestrian lipoma to the inspired SMARCA4-deficient undifferentiated malignancies. Most newly minted tumor variants (eg, sclerosing mucoepidermoid carcinoma with eosinophilia) and enigmatic disease entities (eg, pleomorphic hyalinizing angiectatic tumor) are addressed. Information on targeted therapy is on offer pro re nata and in an exceptionally crisp chapter entitled “Application of Modern Techniques.” The latest classification systems are applied; however, in a welcome departure from the newest World Health Organization classification, the term “invasive ductal of no special type” is used rather than the hapless nomenclature of “invasive breast carcinoma of no special type.” Any sizable textbook of surgical pathology that spans nearly 2,500 pages and is authored by more than five dozen “global authorities” would be expected to offer ample attention to the diseases most likely to be contended with in routine practice. In this regard, Fletcher’s book mostly delivers. There are other competing multivolume and multiorgan surgical pathology textbooks that offer equally credible content and may be relatively even more expansive (mainly by virtue of including nontumor conditions). True to the title, nonneoplastic ailments are largely skipped. One would have to look elsewhere for deliberation of topics such as inflammatory bowel disease, dysfunctional uterine bleeding, and most infectious diseases. Some of the latter (eg, hepatitis) are discussed only in the context of neoplasms. Nevertheless, notwithstanding the title, macroscopic examination of specimens is accorded its rightful place. Some of the book’s rich pickings are worth sharing in this space. Fletcher reminds us that “to diagnose a tumor in the absence of clear and complete clinical data is foolhardy, dangerous, and sometimes impossible.” Some unsavory trends are bemoaned (eg, “it is troubling that many commercial tests are being marketed directly to clinicians and patients, who are unable to distinguish snake oil from clinically worthwhile testing”). It is opined that trends du jour should not be blindly pursued (eg, “despite bold claims and goals, artificial intelligence and deep learning have had little impact on this field as yet”). One is warned against the obvious snare regarding pathologic diagnosis (ie, “by virtue of simple statistical probability, common things remain common; therefore do not be tempted into an esoteric (or exciting) diagnosis”). Perhaps, the one factor that sets Fletcher’s book apart is the equilibrium between the old and the new, manifested in no small measure throughout its pages. Surgical pathologists of a certain age will take comfort in Fletcher’s assertion that “conventional morphologic and immunohistochemical assessment has continued to hold sway as the preeminent, most reliable, and most effective means of providing a diagnosis and prognostic assessment.” Be that as it may, the forward-looking among us need not be disappointed: the book does detail the utility of SYT-SSX1 and SYT-SSX2 fusion genes in validating the diagnosis of synovial sarcoma whenever conventional pathology is found wanting.

Topics & Concepts