Elliott Foucar

Neuroendocrine (Merkel cell) carcinoma of the skin. A histologic and ultrastructural study of two cases.

The clinical, histologic, and ultrastructural features of two cases of a primary cutaneous neuroendocrine neoplasm probably arising from Merkel cells are presented and compared with previously reported examples. This recently described tumor arises in the dermis of elderly individuals, is often locally aggressive, may metastasize to regional lymph nodes, and eventually may cause death. Microscopically, sheets of primitive cells fill and expand the dermis. Ultrastructural study of our cases revealed morphologic similarities to normal cutaneous Merkel cells, including peripherally situated dense-core neurosecretory-like granules, zonula adherens-type intercelluar junctions, prominent Golgi apparatus, and varying numbers of mitochondria and rough endoplasmic reticulum. This unusual tumor is readily confused with cutaneous lymphoma and various undifferentiated primary or metastatic neoplasms by conventional light microscopy. The definitive diagnosis can be made only by electron-microscopic examination.

The Ophthalmologic Manifestations of Sinus Histiocytosis with Massive Lymphadenopathy

Of 113 cases of sinus histiocytosis with massive lymphadenopathy, 13 patients had ophthalmic infiltrates. Eleven of the 13 had infiltrates in the orbital soft tissues, and five of these patients also had eyelid disease. One patient had infiltrates only within the eyelid, and one without disease in the orbit or eyelid had extensive infiltrates in the uveal tract. The microscopic differential diagnosis included a variety of lymphoreticular malignancies, storage diseases, histiocytosis X, rhinoscleroma, tuberculosis, and inflammatory pseudotumor of the orbit. These 13 patients with ophthalmic disease were similar clinically and pathologically to patients with sinus histiocytosis with massive lymphadenopathy who did not have ophthalmic disease.

The neurologic manifestations of sinus histiocytosis with massive lymphadenopathy

Sinus histiocytosis with massive lymphadenopathy is a benign pseudolymphomatous disease with distinctive microscopic features. Painless cervical adenopathy is the most characteristic clinical finding, although other node groups and extranodal sites may be involved. Of 200 patients in a case registry, 8 had neurologic symptoms. The lesions included vertebral canal and intracranial infiltrates and a destructive vertebral body lesion. Two patients had both cord compression and intracranial disease; one of them died after 10 years of disease. Seven patients were alive 1 to 15 years after disease onset.

Classification in anatomic pathology.

Classification is the activity that allows pathologists to arrange the bewildering morphologic manifestations of disease into comprehensible order Ideally, our precise diagnoses would each be based on some timeless biological law of nature, and these diagnoses would group together patients with identical clinical manifestations and responses to therapy. However, in spite of the amazing success of pathology classification, it is apparent to everyone that diagnostic disagreements are common, and that patients who exactly fit into a diagnostic category often have markedly different disease courses and responses to therapy. At this time, it is unclear how quickly the potential of genomic medicine will be translated into revolutionary changes in pathology classification. However, it is clear that the rules of classification are part of the foundation of diagnostic pathology and that there is a high likelihood that pathology classification will undergo substantial changes in the next few years. This article reviews the topic of classification for pathologists who will practice during these interesting times.

Evidence-Based Pathology and Tort Law: How Do They Compare?

All physicians, including pathologists, work in an environment where most diagnostic problems can be resolved using the certainty of widely accepted facts, and therefore major diagnostic disagreements are uncommon. However, some degree of uncertainty is inevitable when dealing with complex biological systems, and this uncertainty is one factor leading to disagreements. It has increasingly been accepted that an evidence-based approach to both scientific investigation and medical practice is the best approach to reducing uncertainty. Unfortunately, due to deficiencies in current knowledge, some areas of uncertainty cannot be resolved scientifically, and pathologists must rely on the ad hoc use of factors such as authority, consensus, experience, and best judgment to resolve disagreements.