Benign atypical junctional melanocytic hyperplasia associated with intradermal nevi: a common finding that may be confused with melanoma in situ.

Over the past few years, consultation cases thought to represent melanoma in situ have been received that consisted of otherwise normal intradermal nevi with an abnormal but benign junctional proliferation of melanocytes that we have termed benign atypical junctional melanocytic hyperplasia. In order to evaluate the incidence of this feature, 400 cases of intradermal nevi were reviewed. Of these, 25 (6.2%) qualified for inclusion, making this a rather common phenomenon. Clinically, patient ages ranged from 18 to 64 years (mean, 35 years), with a male to female ratio of 1:1. Face (40%) and back (32%) were the most common locations. Histologically, the lesions were predominantly dome-shaped with an intradermal component consisting of conventional nevus cells. Most importantly, each lesion exhibited prominent individual nevomelanocytic cells dispersed at uneven intervals along the dermoepidermal junction in insufficient numbers to be considered compound nevi. The cells exhibited abundant pale to clear cytoplasm, an increased nuclear:cytoplasmic ratio, and often exhibited prominent nucleoli. However, these lesions could be distinguished from melanoma in situ by the lack of several features including lateral spread, upward epidermal migration, marked cytologic atypia, finely granular "smoky" melanin pigment, mitotic figures, and a subjacent host inflammatory response. All cases behaved in a benign fashion. Although benign atypical junctional melanocytic hyperplasia is a relatively common histological curiosity, it is a potential pitfall in the diagnosis of pigmented lesions.

Solitary fibrous tumor of the skin.

Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm that most commonly involves the pleura, but is increasingly more often observed in extrapleural locations. A 37-year-old woman presented with an SFT involving the skin and subcutaneous tissue of the scalp. Histologically, SFT is well circumscribed and composed of uniform spindle cells arranged in interlacing fascicles. It exhibits alternating hypercellular and hypocellular areas with abundant thick, often keloid-like, hyalinized collagen. Hemangiopericytoma-like areas are frequently prominent. Immunohistochemical markers for smooth muscle, neural, and epithelial differentiation are negative, but generalized positivity for CD-34 is characteristic. Because of the expanding spectrum of anatomic involvement of SFT, it is not surprising that on rare occasions this tumor may involve the skin.

Cutaneous lymphoepithelial neoplasms.

Lymphoepithelial neoplasms are a heterogeneous group of biphasic tumors that contain both epithelial and lymphoid components. Most of these tumors are primarily epithelial with a secondary lymphoid infiltrate and illustrate the basic cell trafficking that occurs in the skin. Included are benign cutaneous lymphadenoma, malignant lymphoepithelioma-like carcinoma, heterotopic dermal thymus, and several miscellaneous lesions that may have a prominent lymphoid infiltrate. Familiarization with their characteristic features will aid in the recognition of these relatively uncommon but often distinct entities.

Potential clinical applications of C-reactive protein.

This article reviews the clinical applications of C-reactive protein (CRP). This acute-phase protein is a distinct and sensitive marker for inflammation and tissue injury. It is a simple, fast, and relatively inexpensive latex agglutination test. The aspects of CRP reviewed include diagnostic support, serial measurements to evaluate disease course and therapeutic response, and screening studies.