Defining the Histopathological Term Atypical Intraepidermal Melanocytic Proliferation: A Retrospective Cross-Sectional Study.

BACKGROUND: Atypical intraepidermal melanocytic proliferation (AIMP) is a general term assigned to melanocytic proliferations of uncertain biological potential when a definitive histopathological diagnosis cannot be achieved. There are few data available describing the possibility of malignancy of AIMP, or ways to further define diagnosis. OBJECTIVE: To determine the rate of diagnostic change of AIMP to melanoma or melanoma in situ (MIS) after conventional excision. In addition, to determine the role of immunohistochemistry (IHC) in defining AIMP biopsies. METHODS: Retrospective cross-sectional, single-center review of biopsies with a diagnosis of AIMP with a follow-up conventional excision from 2012-2016 was performed. In a separate analysis, a search was performed for AIMP biopsied lesions in which IHC was subsequently performed. RESULTS: The rate of diagnostic change of AIMP to MIS was 4.8% (8/167) after excision. Punch biopsy was a risk factor for diagnostic change to MIS (odds ratio 12.94, confidence interval 2.56-65.38, P = 0.008). The rate of diagnostic change of AIMP biopsies after examining with IHC was 21.3% (34/160) to MIS and 4.4% (7/160) to melanoma. CONCLUSION: The possibility of malignancy of AIMP lesions must be taken into consideration when counseling patients and when planning treatment options. IHC is a useful tool and should be used in the evaluation of AIMP specimens.

Pigmented Lesions of the Nail Unit.

Pigmented lesions of the nail unit are commonly encountered in the clinical setting. Yet, they often present a unique challenge to clinicians because of a broad differential diagnosis or unfamiliarity with clinical and histopathologic features. A wide variety of causes exist ranging from benign lesions such as subungual hemorrhage to malignant lesions such as subungual melanoma. Identifying the underlying cause is key to appropriate management and follow-up in these patients. Although emerging clinical tools such as dermoscopy can be very useful in evaluation of these lesions, histopathologic analysis remains the gold standard. In this review, we discuss and provide a summary of important clinical and histopathological concepts of pigmented lesions of the nail unit with special focus on longitudinal melanonychia, melanotic macule, melanocytic nevus, subungual melanoma, along with discussion of some nonmelanocytic lesions.

Role of Skin Biopsies in the Diagnosis of Hemophagocytic Lymphohistiocytosis.

This is a report of a 15-year-old female who presented with a skin eruption and clinical features consistent with severe sepsis and septic shock. A diagnosis of acquired hemophagocytic lymphohistiocytosis (HLH) was made and confirmed by bone marrow analysis. Skin biopsy showed hemophagocytosis and CD163-positive staining of macrophages. We briefly review the clinical, histologic, and laboratory findings of hemophagocytic lymphohistiocytosis in addition to the potential role of skin biopsies in this condition.

Palisaded Granuloma on the Nose: An Atypical Presentation of Granuloma Annulare.

Granuloma annulare (GA) is a common, asymptomatic dermatosis of unknown etiology. Many variants exist, among them widespread papules, papules in photodistribution, papules marked by tiny crusts ("perforating" GA), patches, plaques, and nodules (subcutaneous GA). The histopathological hallmark is a palisaded histiocytic infiltrate surrounding a central area of degenerated collagen with abundant mucin deposits. We report 2 women who presented with persistent nodules on the nose, which, on histopathological examination, showed a palisaded granuloma. We propose that these cases represent an unusual variant of GA occurring on the nose.

Extraocular Sebaceous Carcinoma-A Clinicopathologic Reassessment.

Sebaceous carcinoma is an aggressive adnexal neoplasm with sebaceous differentiation. Few reports have described the histopathologic characteristics of the sebaceous carcinoma occurring extraocularly. Seventy-two cases of extraocular sebaceous carcinoma were identified from the database of a Dermatopathology Laboratory from January 1, 2007 to May 31, 2013. More cases occurred in men (60%), with a mean age at diagnosis of 65.8 years (range 39-99 years). Neoplasms were histopathologically classified as well-differentiated (22%), moderately differentiated (67%), and poorly differentiated (11%). Sixty-seven percent (67%) of cases demonstrated a squamoid growth pattern and thirty-three percent (33%) demonstrated a basaloid growth pattern. A majority of the neoplasms histopathologically classified as well-differentiated (94%) and moderately differentiated (65%) demonstrated a squamoid growth pattern. Ten percent (10%) of cases exhibited cystic histopathologic changes. The histopathological features reported in this study aid in the understanding of extraocular sebaceous carcinoma and its eventual diagnosis and classification.

Clear-Cell Atypical Fibroxanthoma: A Combined Immunohistochemistry Analysis.

Atypical fibroxanthoma is considered to be a low-grade sarcoma, characterized by a proliferation of bizarre spindled cells. A case of a rare variant of this tumor, a clear-cell atypical fibroxanthoma, presenting with rapid growth on a 63-year-old female, is reported. The differential diagnosis of a clear cell proliferation and a review of the immunohistochemistry markers used in the diagnosis of atypical fibroxanthoma are discussed. In particular, the usefulness of markers such as CD10, procollagen 1, CD68, CD163, CD99, and S100A6, and the importance of negative markers such as S100, cytokeratin, and desmin are emphasized. Furthermore, the development of a keratoacanthoma at the site of previous Mohs surgery is recounted.

Acquired segmental neuromas.

Neuromas are benign hyperplastic proliferations of normal peripheral nerve components. These can be associated with some genodermatoses, namely Cowden syndrome and multiple endocrine neoplasia (MEN) 2B, especially when numerous lesions are present. Given the potential for malignancy (such as breast cancer, pheochromocytoma, and thyroid cancer) associated with these syndromes, other features indicative of either syndrome should be evaluated in patients presenting with multiple cutaneous neuromas. The evaluation should include a thorough family history and complete physical, dermatologic, and ophthalmologic exams as well as thyroid studies. We report, herein, the case of an 8-year-old female with cutaneous neuromas distributed segmentally with no other associated finding suggestive of an underlying syndrome.