Michael G. Hitchcock

Utility of Rush Paraffin‐Embedded Tangential Sections in the Management of Cutaneous Neoplasms

Background. Mohs micrographic surgery (MMS) modified by the use of tangential, formalin‐fixed, paraffin‐embedded histologic specimens is advantageous in treating selected skin neoplasms. Objective. To review the use of our experience with a modification of MMS to treat lentigo maligna melanoma (LMM), lentigo maligna (LM) and other melanoma in situ (MIS) lesions, dermatofibrosarcoma protuberans (DFSP), atypical fibroxanthoma (AFX), and angiosarcoma. Methods. Our experience utilizing a modification of MMS in the treatment of 77 patients with LM or other MIS, 23 patients with LMM, 11 patients with DFSP, 1 patient with AFX, and 1 patient with angiosarcoma was reviewed. Length of follow‐up and rate of recurrence were examined. A literature review of this pertinent modification of the Mohs technique was performed. Results. One hundred fourteen patients underwent MMS for melanocytic (LM, MIS, LMM), spindle cell (DFSP, AFX), and vascular malignant neoplasms. One patient developed locally recurrent LM and one patient with LMM developed satellite metastasis. Regional lymph node metastasis occurred in one patient with LMM and in a patient with angiosarcoma. Conclusion. The use of Mohs micrographic surgery in conjunction with rush formalin‐fixed, paraffin‐embedded tangential histologic sections provides the accuracy and tissue conservation of the Mohs procedure while ensuring more confident interpretation of histology in cases of lentigo maligna, lentigo maligna melanoma, dermatofibrosarcoma protuberans, atypical fibroxanthoma, and angiosarcoma.

Panniculitis: Recent developments and observations

Dermatopathologists rarely greet a biopsy of panniculitis with total confidence that a specific, definitive diagnosis will be rendered. As with many other areas in dermatopathology, our understanding of the pathogenesis of many forms of panniculitis is incomplete. This article examines a subset of panniculitis primarily from a pathogenetic standpoint, with the intention of providing a differential diagnosis for those cases in which ischemic changes are seen in the subcutis. The diverse group of conditions evoked by this approach also shares the distinction of having been the focus of nosologic and causative controversy, both historically and currently. In particular, stasis-associated sclerosing panniculitis, vascular calcification-cutaneous necrosis syndrome (calciphylaxis), oxalosis, and nodular vasculitis-erythema induratum are examined in depth. Erythema nodosum and variants, other granulomatous panniculitides, and panniculitides showing cytophagocytosis are also discussed with current perspectives.

Cutaneous melanoma with myxoid features: twelve cases with differential diagnosis.

Substantial myxoid change can occur in malignant melanoma, but its importance in primary disease has not been systematically evaluated. This report describes the clinical, microscopic, histochemical, and immunohistochemical findings in 12 patients with primary cutaneous malignant melanoma with myxoid features. The tumors presented as solitary lesions situated on the limbs (six lesions), trunk (four lesions), and head and neck (two lesions). The patients included six women and six men, whose ages ranged from 26 to 95 years, with a mean of 63 years. Breslow thickness varied from 0.48 mm to more than 12 mm, with a mean of more than 3.2 mm. Clinical follow-up for an average of 22 months showed one local recurrence, but no evidence of metastases yet. In all cases, there was a combination of myxoid and nonmyxoid areas. A minimum of 15% myxoid cross-sectional area was required for inclusion in the study, and up to 80% was observed. The pale blue mucin identified on hematoxylin and eosin staining was sensitive to hyaluronidase and positive for alcian blue in the 10 cases stained. Immunohistochemical staining was positive for S-100 in all 9 cases stained, positive for HMB-45 in 9 (90%) of 10, and negative for cytokeratin in all 9 cases in which myxoid melanoma remained in the block after previous sections. The presence of myxoid stroma did not define a biologically significant subgroup of melanoma. Only in cases with extensive (>50%) myxoid stromal effacement of the melanoma was there a major diagnostic hurdle. The diagnosis of primary cutaneous melanoma with myxoid features was seldom as problematic as metastatic myxoid melanoma. Positive S-100 stains, negative cytokeratin immunohistochemical stains, and hyaluronidase-sensitive alcian blue staining assisted in the diagnosis of this entity.

Primitive Neuroectodermal Tumors of the Biliary and Gastrointestinal Tracts: Clinicopathologic and Molecular Diagnostic Study of Two Cases

Primitive neuroectodermal tumor (PNET) is a prototypic malignant small round cell tumor of childhood that is characterized in most cases by t(11;22) resulting in an EWS-FLI1 gene fusion. Once thought to be uncommon, PNET now accounts for almost 20% of malignant soft tissue tumors in children. Increased recognition of PNET is partly due to advances in immunohistochemistry and molecular diagnostics, which have led to the identification of the tumor in non-classical sites. We report the clinical, histologic, immunohistochemical, and molecular findings of two visceral PNETs of the digestive system—one involving the small intestine and the other involving the hepatic duct. Histologically, each tumor was composed of malignant small cells growing in sheets, nests, and lobules; the tumor cells of both cases showed characteristic immunoreactivity for vimentin and O13 (CD99). Reverse transcription-polymerase chain reaction (RT-PCR) analysis for t(11;22) using nested primers was performed with RNA extracted from paraffin-embedded, formalin-fixed tissue and demonstrated an EWS exon 7 to FLI1 exon 5 fusion in both cases, confirmed by Southern blot hybridization and DNA sequence analysis. These results illustrate the expanded clinicopathologic profile of PNET, and demonstrate that visceral PNETs, despite their unusual sites of presentation, maintain the characteristic immunohistochemical and genetic features of PNETs at more conventional sites.

Eccrine gland infiltration by mycosis fungoides

After identifying prominent eccrine infiltration by atypical lymphocytes in a biopsy of tumor stage mycosis fungoides (MF), we sought to determine the pattern of eccrine epithelial infiltration in MF. The frequency, intensity, and distribution of infiltration of eccrine gland structures, including acrosyringium, duct and coil epithelium, was studied by examining 71 biopsy specimens from 42 patients with MF in which eccrine structures were present. These were obtained from a retrospective review of pathologic specimens from Duke University Medical Center from 1992 and 1993. At least focal eccrine infiltration was noted in 23 of the 71 biopsy specimens (32%). Immunohistochemical confirmation of T-lymphocyte phenotype was performed in the 23 cases with positive reaction to antibodies CD3 and CD45RO and negative reaction with CD20. Folliculosebaceous units were present in 22 of the 71 biopsy specimens and were at least focally involved by MF in 11 (50%) in this series. A control group of biopsy specimens of reactive dermatoses were characterized by more superficial location of lymphocytes, with more spongiosis and epithelial degenerative changes. These findings further illustrate the epitheliotropic behavior of MF.

Cutaneous clear-cell granular cell tumors: the histologic description of an unusual variant

Background:  Granular cell tumors (GCTs) are neoplasms showing nerve sheath differentiation that can arise in the skin but, to our knowledge, have not been associated with significant clear‐cell morphology.

Lymphomatoid papulosis : Successful weekly pulse superpotent topical corticosteroid therapy in three pediatric patients

Abstract: Lymphomatoid papulosis is a T‐cell proliferation that occurs primarily in adults but has been well described in children. Lesions may regress spontaneously but often leave residual scarring and, as a result, intervention frequently is considered. Therapeutic modalities commonly employed for adults with lymphomatoid papulosis may be poorly tolerated by pediatric patients. We present a series of three children with lymphomatoid papulosis treated with superpotent topical corticosteroids (halobetasol or clobetasol propionate). When applied twice daily for 2 to 3 weeks followed by weekly pulsed application, this treatment resulted in complete resolution of nearly all cutaneous lesions. Three ulcerated lesions, occurring in two patients, required adjuvant therapy with intrale‐sional triamcinolone. To date one patient remains free of cutaneous disease and two children experience occasional new lesions that respond to renewed treatment with topical clobetasol propionate. None of the children have evidence of systemic disease. We conclude that pulsed application of a superpotent topical corticosteroid is efficacious and safe in the management of cutaneous lesions of lymphomatoid papulosis and avoids the risks often associated with more aggressive interventions. Since these agents do not alter the risk of subsequent malignancy, careful ongoing surveillance of children with lymphomatoid papulosis is imperative.