G. Peter Sarantopoulos

Immunohistochemical characteristics of melanoma.

Melanoma has a wide spectrum of histologic features which mimic epithelial, hematologic, mesenchymal, and neural tumors. Immunohistochemistry has been the primary tool to distinguish melanomas from these other tumors; it has also been studied for use as an adjunct to distinguish benign and malignant melanocytic tumors and to elucidate prognosis. Furthermore, there has been extensive effort to find a suitable marker to differentiate spindle cell and desmoplastic melanoma from other tumors. We have reviewed the literature investigating melanocytic differentiation markers, proliferation markers, immunomodulatory markers, signaling molecules, and nerve growth factors and receptors. Despite the proliferation of immunohistochemical markers, S‐100 remains the most sensitive marker for melanocytic lesions, while markers such as HMB‐45, MART‐1/Melan‐A, tyrosinase, and MITF demonstrate relatively good specificity but not as good sensitivity as S‐100. No marker has proven useful in distinguishing spindle cell and desmoplastic melanomas from other tumors. Ki67 remains the most useful adjunct in distinguishing benign from malignant melanocytic tumors. None of the markers reviewed has been shown conclusively to have prognostic value for melanocytic neoplasms.

Immunohistochemical Analysis of Lung Carcinomas With Pure or Partial Bronchioloalveolar Differentiation

CONTEXT In 1999, the World Health Organization redefined bronchioloalveolar carcinomas (BACs) as those neoplasms with only a pure lepidic growth pattern and no invasion. OBJECTIVES The present study examined 45 lung cancers with a BAC component (1) to determine whether these tumors would be classified as BACs by current World Health Organization standards, (2) to quantitate the BAC component within these tumors, and (3) to see if phenotypic differences exist between the so-called invasive and noninvasive regions of these tumors. DESIGN Retrospective review of hematoxylin-eosin-stained slides and classification of histologic grade, tumor subtype, and percentage of pure BAC pattern, with further characterization by immunohistochemical staining for thyroid transcription factor 1, cytokeratin 7, cytokeratin 20, and Ki-67 antibodies. RESULTS Only 7 (15.6%) of the 45 tumors examined could be classified as BAC by current strict World Health Organization criteria. Those tumors, classified as nonmucinous and mixed, showed similar immunohistochemical staining for cytokeratin 7, cytokeratin 20, and thyroid transcription factor 1; mucinous tumors showed disparate staining. Significant differences in immunohistochemical staining and tumor cell proliferation were seen for the regions of tumors designated as lepidic, infiltrative, and leading edge and for the regions of tumors with different histologic grades (ie, well, moderately, and poorly differentiated). CONCLUSIONS Nonmucinous and mixed BACs are phenotypically similar and show identical immunohistochemical staining patterns; mucinous tumors, on the other hand, show disparate immunohistochemical staining. Pulmonary neoplasms designated as adenocarcinomas with a BAC component represent a heterogenous group with a range of cell types, differentiation, growth, and immunophenotypes. Within an individual neoplasm, there are regional differences in these parameters as well.

Longitudinal melanonychia of the toenails with presence of Medlar bodies on biopsy

Abstract:  A 9‐year‐old girl presented with a 2‐year history of pigmented streaks on her second right toenail as well as on her fourth and fifth left toenails. The patient was otherwise asymptomatic with no other physical findings. Owing to parental concern, a biopsy was performed, which revealed numerous bacteria as well as Medlar bodies overlying the nail bed with no evidence of a nevomelanocytic lesion. To our knowledge, this is the first report of Medlar bodies causing pigmented streaks in the toenails.

Dyshidrotic mycosis fungoides

Mycosis fungoides (MF) represents the most common type of cutaneous T‐cell lymphoma (CTCL). CTCL often progresses through patch, plaque and tumor stages but can also manifest with varied clinical presentations. MF rarely presents in vesiculobullous fashion, in which vesicles or bullae develop in pre‐existing plaques or on the trunk or proximal extremities. We report a patient who presented with a vesiculobullous eruption on the palms and soles, resembling dyshidrotic dermatitis, which we believe represents dyshidrotic MF.

Fungal leukocytoclastic vasculitis as a presentation of systemic vasculitis in a patient with systemic lupus erythematosus

Patients with systemic lupus erythematosus (SLE) commonly have vasculitis with cutaneous involvement. Disease activity associated with SLE is frequently responsible for the vasculitis, although infection is also important to consider. We describe a young woman with SLE who was found to have leukocytoclastic vasculitis due to Candida albicans.

Scalp paraffinoma underlying squamous cell carcinoma.

We report the case of an 84-year-old man with multiple squamous cell carcinomas located on his bald scalp, arising in association with underlying paraffinoma. Histologically, poorly differentiated, acantholytic squamous cell carcinomas were located above characteristic pseudocystic spaces. Carcinomas have been reported in association with penile and breast paraffinomas, but we are unaware of any reports of squamous cell carcinoma arising over a scalp paraffinoma.