Evaluation of the Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MPATH-Dx) classification scheme for diagnosis of cutaneous melanocytic neoplasms: Results from the International Melanoma Pathology Study Group.

Background: Pathologists use diverse terminology when interpreting melanocytic neoplasms, potentially compromising quality of care.

Objective: We sought to evaluate the Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MPATH-Dx) scheme, a 5-category classification system for melanocytic lesions.

Methods: Participants (n = 16) of the 2013 International Melanoma Pathology Study Group Workshop provided independent case-level diagnoses and treatment suggestions for 48 melanocytic lesions.

Cellular Blue Nevomelanocytic Lesions: Analysis of Clinical, Histological, and Outcome Data in 37 Cases.

Cellular blue nevomelanocytic lesions (CBNLs) frequently pose diagnostic problems to pathologists, and their biological potential may be difficult to establish. In this study, the authors have analyzed the clinical, histological, and outcome data of 37 cellular blue nevomelanocytic lesions and the molecular characteristics of 4 lesions. The cohort of cases comprised 8 cellular blue nevi (CBNs), 17 atypical cellular blue nevi (ACBNs), and 12 blue-nevus-like melanomas (BNLMs) with a mean follow-up of 5 years.

Granular cell variant of epithelioid cell histiocytoma.

Classic granular cell tumors (GCTs) stain strongly and uniformly positive for S100 protein and are believed to show Schwann cell derivation. Polypoid cutaneous tumors composed of cells with large nuclei and abundant granular cytoplasm that do not stain for S100 protein or show apparent Schwannian differentiation have been reported by several groups under names including "primitive polypoid granular cell tumors," "dermal nonneural granular cell tumor," and "primitive nonneural granular cell tumors of skin." We report a polypoid tumor composed of S100-negative epithelioid cells with abundant eosinophilic granular cytoplasm that meets diagnostic criteria for (primitive polypoid dermal) nonneural GCT but also meets criteria for a granular cell variant of epithelioid cell histiocytoma.

The limited specificity of histological examination in the diagnosis of dysplastic nevi.

Dysplastic nevi were originally described as a distinct entity with specific clinical and histological features of importance as direct precursors of malignant melanoma and as markers of patients at increased risk of developing melanoma in the setting of familial melanoma. Nevi with the clinical and histological features described first as 'B-K moles' and later as 'dysplastic nevi' clearly do exist and do sometimes represent melanoma precursors or melanoma risk markers, but it is now recognized that most dysplastic nevi never progress to melanoma, that the histological features originally described in nevi in familial melanoma patients are poorly correlated with dysplastic nevi as they are defined clinically, and that overlapping or identical histological features are found in a variety of other melanocytic lesions including small (< 5 mm) melanocytic nevi, lentiginous nevi, atypical (dysplastic) lentiginous nevi, lentiginous melanoma, lentigo maligna and nevi in an ever-growing number of 'special sites'. This article will briefly review the evolution of our understanding of the histological range of nevi and the histological differential diagnosis of dysplastic nevi.

Multiple hybrid granular cell tumor-perineuriomas.

Hybrid peripheral nerve sheath tumors (PNSTs) are recently recognized, rarely reported entities. Very few hybrid PNSTs with elements of perineurioma have been reported. We report a case of a 47-year-old man who presented with multiple (>20) cutaneous nodules on all 4 extremities, present since childhood.

Smooth muscle hamartoma associated with a congenital pattern melanocytic nevus, a case report and review of the literature.

Smooth muscle hamartoma (SMH) is a rare benign congenital or acquired lesion sometimes associated with Becker's nevus (Becker's melanosis). We report an unusual lesion with combined features of SMH and melanocytic nevus. The patient is a 49-year-old male with a history of a changing 'mole' on the left upper back.

Atypical cellular blue nevi (cellular blue nevi with atypical features): lack of consensus for diagnosis and distinction from cellular blue nevi and malignant melanoma ("malignant blue nevus").

The distinction of cellular blue nevi (CBN) with atypical features ["atypical" CBN (ACBN)] from conventional CBN and malignant melanomas related to or derived from CBN remains a difficult problem. Here, we report on the diagnosis of various cellular blue melanocytic neoplasms by 14 dermatopathologists who routinely examine melanocytic lesions. Three parameters were assessed: (1) for between rater analyses, we calculated interobserver agreement by the kappa statistic (regardless of whether the diagnosis was correct).

Clinicopathologic, immunophenotypic, and molecular cytogenetic fluorescence in situ hybridization analysis of primary and secondary cutaneous follicular lymphomas.

Although primary cutaneous follicular lymphoma (FL) is considered a distinct variant of FL in the World Health Organization classification ("cutaneous follicle center lymphoma"), its biologic relationship to nodal FL remains controversial. The clinical, morphologic, immunophenotypic, and molecular cytogenetic features of 17 patients with primary cutaneous FL were studied and compared with 16 patients with secondary cutaneous FL. The head and neck region was the most frequent site at initial skin presentation in both the primary and secondary cases.

Mohs micrographic surgery for the eradication of phaeohyphomycosis of the hand.

Background: Phaeohyphomycosis is a rare mycotic infection that is caused by dematiaceous fungi requiring surgical excision or long-term use of oral antifungal agents for treatment.

Objective: To report a case of phaeohyphomycosis of the dorsal hand successfully cleared with Mohs micrographic surgery.

Methods: We performed Mohs micrographic surgery on phaeohyphomycosis of the dorsal hand.

Are en face frozen sections accurate for diagnosing margin status in melanocytic lesions?

To assess the diagnostic accuracy of margin evaluation of melanocytic lesions using en face frozen sections compared with standard paraffin-embedded sections, we studied 2 sets of lesions in which en face frozen sections were used for analysis of surgical margins (13 from malignant melanomas [MMs] and 10 from nonmelanocytic lesions [NMLs]). Routine permanent sections were cut after routine processing. The slides were mixed and coded randomly.

Histological characteristics of metastasizing thin melanomas: a case-control study of 43 cases.

Objective: To study clinical and histological features associated with metastasizing thin melanomas (MTMs).

Design: Case-control study of clinicopathological features of patients with MTMs by a panel of 10 dermatopathologists.

Setting: Members of the North American Melanoma Pathology Study Group selected the cases from the melanoma databases at 8 academic institutions.