Reticulin and NM23 staining in the interpretation of lymph nodal nevus rests.

Melanocytic nevus rests in lymph nodes are a known diagnostic challenge, especially in patients with a history of melanoma. Reticulin and NM23 have been studied in this context. The pattern of reticulin staining in melanomas surrounds groups/nests of melanocytes but individual cells in benign nevi. NM23, a metastasis-suppressor gene, has an association with metastatic potential in melanomas and some carcinomas. Twenty-eight cases (14 cases of metastatic melanoma to lymph nodes and 14 cases of lymph node nevus rests, all confirmed with Melan-A staining) were stained with reticulin and NM23. The pattern of reticulin staining was reported as surrounding groups if staining was noted in approximately 5-10 melanocytes in greater than 50% of the lesion but was otherwise reported as surrounding individual melanocytes. Cytoplasmic staining was considered to represent reactivity for NM23. Reticulin staining around groups of melanocytes was identified in all 14 cases of metastatic melanoma. Regarding nodal nevus rest cases, 12 of 14 cases (86%) demonstrated staining around individual melanocytes, whereas in 2 cases, reticulin surrounded melanocytic groups. NM23 staining was equivocal in all cases. Reticulin staining reliably invests groups of melanocytes in cases of metastatic melanoma, whereas in nodal nevus rests, it predominantly surrounds individual melanocytes. NM23 demonstrated no discriminatory value in this analysis. In cases in which a collection of melanocytes is present within a lymph node, reticulin deposition around individual melanocytes supports a diagnosis of lymph nodal nevus rest.

Nevic mitoses: a review of 1041 cases.

The presence of dermal mitotic figures is helpful in identifying malignant melanocytic lesions but occasionally occur in benign nevi. We aim to determine a "benchmark" mitotic frequency for a wide variety of nevi. We prospectively collected 1041 cases of benign melanocytic nevi and reviewed them for the presence of mitotic figures. Specimens were collected from female (62%) and male (38%) participants, ages ranged from 1 to 90 years. Nevus types included compound melanocytic nevi (CMN), intradermal melanocytic nevi, junctional melanocytic nevi, lentiginous CMN (LCMN), lentiginous junctional melanocytic nevi, blue nevi, deep penetrating nevi, and pigmented spindle cell nevi. Nevi with congenital, mildly dysplastic, and Spitzoid features were included. A total of 82 of 1041 (7.9%) nevi contained one or more mitotic figures. Most (76.1%) mitoses were found in the papillary dermis. Single mitotic figures were more common (80.4%) than 2 (15.9%) or 3 (3.7%) within a single specimen. Of all cases containing mitotic figures, the most common nevus type was CMN. The nevus type most frequently demonstrating mitotic figures was CMN. The most common body site among cases with mitotic figures was trunk (53.7%), whereas the body site with the largest proportion of nevi demonstrating mitotic figures was special site (10.9%). The percentage of nevi containing mitotic figures was nearly the same among female (7.9%) and male (7.8%) participants. Results of this large review confirm that mitotic figures, even multiple ones, do not preclude benignity in a variety of melanocytic nevi.

Cutaneous T-cell lymphoma occurring with a melanocytic proliferation, masquerading as a nonhealing ulcer with reactive changes.

Two of the most challenging areas in dermatopathology are lymphoproliferative disorders and melanocytic lesions. We present a case of peripheral T-cell lymphoma occurring with an intradermal melanocytic proliferation. A 63-year-old Caucasian man presented with a 12-cm edematous, erythematous to violaceous, scalp ulceration that had enlarged over six months. Previous biopsies showed reactive changes which were concerning for infection. The last biopsies showed small to intermediate sized, angulated cells with clear cytoplasm within the dermis, with extension into the epidermis. These cells stained positive with markers for CD3, CD45RO and CD43, yet showed decreased expression of pan-T-cell markers CD5 and CD7, and absent expression of CD4, CD8, CD56 and CD57 and EBV. Molecular studies showed a clonal T-cell receptor gamma chain gene rearrangement. The diagnosis was peripheral T-cell lymphoma, unspecified. Another biopsy from an indurated area separate from the ulcer showed scattered, enlarged cells embedded in the same lymphocytic infiltrate. No mitotic figures were identified. These cells stained for S100 and Melan-A, in a partly nested arrangement. This was felt to represent a melanocytic nevus. This case likely represents an extraordinary coincidence of two distinctly different neoplasms.

Multicentric reticulohistiocytosis and urologic carcinomas: a possible paraneoplastic association.

Multicentric reticulohistiocytosis (MR) is a rare non-Langerhans histiocytosis that is characterized by cutaneous nodules and severe destructive arthritis. Although 25-30% of reported cases have been associated with internal malignancies, the pathophysiology of MR is unknown. Herein, we report two cases of MR that were associated with urologic neoplasms. Because the tumor suppressor gene p53 may play a role in the biology of other histiocytoses, we investigated its p53 immunoexpression in these two cases. Both cases were positive immunohistochemically, but it remains to be seen whether this finding is truly important in the pathogenesis of MR associated with underlying visceral neoplasms.

Circumscribed palmar hypokeratosis: two cases and a review of the literature.

A 60-year-old female and a 59-year-old male each presented with a solitary circumscribed patch of depressed skin of the right thenar palm and right sole, respectively. Both lesions were present for approximately 30 years without a history of trauma or other inciting incident. Histologically, the lesions showed a well-demarcated abrupt decrease in the thickness of the stratum corneum with a central area of thinned stratum corneum and hypogranulosis. Inflammation was absent. Ultrastructurally, keratin filaments were evident in the stratum corneum, and a diminished granular cell layer was apparent. There was a decrease in maturation of the keratinocytes, however, no defects in corneodesmosomes or other ultrastructural components were identified. No evidence of human papilloma virus was detected by in situ hybridization studies. Based on these 2 cases and the 25 cases reported in the literature to date, this entity seems to represent a chronic localized non-inflammatory defect in keratinization on acral sites.