Fontana-Masson stain in fungal infections.

BACKGROUND: Fontana-Masson (FM) staining is a histopathology technique used to identify dematiaceous fungi. The result often guides initial species identification and antifungal treatment; however, there is evidence that nondematiaceous fungi might react with this stain. Few studies in the current literature address this issue. OBJECTIVE: Our aim was to classify the FM staining patterns of common fungal pathogens for use by pathologists attempting to accurately identify fungi on histopathologic examination. METHODS: In total, 132 cases of culture proven mycoses were identified. We stained tissue with 2 different FM protocols and recorded the intensity and distribution of results. RESULTS: There was variability in staining, and many nondematiaceous fungi showed positivity, including Zygomycetes, Aspergillus, and Fusarium spp. LIMITATIONS: The study was limited by the number of cases. Of 132 cases identified, 112 cases had adequate tissue left after sectioning deeper into the block. CONCLUSION: Nondematiaceous fungi frequently stained positive with FM. The course of treatment should not be based on the result of this stain alone. Histopathology should be examined in multiple tissue sections, and therapy should be determined on the basis of clinical context and culture results.

Lesions of the lacrimal caruncle with an emphasis on oncocytoma.

Lesions of the lacrimal caruncle vary widely due to its unique composition. Rarely, dermatologists and dermatopathologists encounter biopsies taken from this location. The aims of this study were to (1) retrospectively review caruncular lesions of the eye examined at Duke University Medical Center and (2) review the literature associated with caruncle pathology with emphasis on oncocytoma. A retrospective search of all lesions of the caruncle examined at Duke University Medical Center from 1991 to 2009 was performed. Fifty-nine lesions of the caruncle were identified. Nevi (40.7%) were the most common lesions observed, although squamous papillomas were the second most common entity (8.5%). Three oncocytomas were identified (5.1%), and were the next most common lesion present at this body site. These 3 entities represented 54.3% of the lesions found in the caruncle. Fifteen percent of the caruncular biopsies contained malignant or borderline malignant lesions, whereas the remaining 85% were benign entities. Most lesions present in the caruncle are benign. Although relatively rare, oncocytomas may be encountered by the dermatopathologist and may be confused for other neoplasms. Oncocytomas should be considered in the differential diagnosis based on this location in addition to histopathologic features.

Neurofibroma with clear cell change.

Cutaneous clear cell proliferations and degenerative change have been seen in a variety of entities including nevi, dermatofibromas, fibrous papules, atypical fibroxanthomas, basal cell carcinomas, and squamous cell carcinomas, to name a few. However, there have been no reports of clear cells within neurofibromas. We received a biopsy and excision from a 61-year-old man with a papule on his right lateral clavicle. The initial biopsy showed a proliferation of clear cells that stained positive with S-100 and focally with CD68. A clear cell granular cell tumor was favored. Subsequent excision showed the same population of clear cells as seen on the initial biopsy. Interestingly, a neurofibroma was also present immediately beneath the clear cells with areas of transition. A p75 stain highlighted both populations of cells. This is the first case of neurofibroma with clear cells reported in the literature. We postulate that the clear cells are due to degenerative change.

Metastatic cutaneous carcinoid tumor mimicking an adnexal poroid neoplasm.

OBJECTIVE: Metastatic cutaneous neoplasms may be difficult to differentiate from primary cutaneous neoplasms. Herein, we report an unusual case of metastatic cutaneous carcinoid tumor mimicking an adnexal poroid neoplasm. METHODS: A 53-year-old male man presented with a neoplasm on the vertex of the scalp, clinically resembling a pigmented basal cell carcinoma. RESULTS: A shave biopsy was suggestive of an apocrine poroma, however, a metastatic carcinoma could not be excluded. After acquiring additional clinical information and the complete excision of the neoplasm, further immunohistochemical stains supported the diagnosis a metastatic carcinoid tumor. CONCLUSION: To our knowledge, this is the first case of metastatic carcinoid tumor reported that has mimicked a poroid neoplasm.