The utilization of spitz-related nomenclature in the histological interpretation of cutaneous melanocytic lesions by practicing pathologists: results from the M-Path study

BACKGROUND

Spitz nevi, atypical Spitz tumors and spitzoid melanomas ('spitzoid lesions') represent controversial and poorly understood cutaneous melanocytic lesions that are difficult to diagnose histologically. It is unknown how these terms are used by pathologists.

METHODS

We describe use of Spitz-related terminology using data from the Melanoma Pathology (M-Path) study database comprising pathologists' interpretations of biopsy slides, a nation-wide study evaluating practicing US pathologists' (N = 187) diagnoses of melanocytic lesions (8976 independent diagnostic assessments on 240 total test cases, with 1 slide per case).

RESULTS

Most pathologists (90%) used the Spitz-related terminology. However, significant variation exists in which specific lesions were diagnosed as spitzoid and in the corresponding treatment recommendations. Recommendations ranged from 'no further treatment' to 'wide excision of 10 mm or greater' with no category capturing more than 50% of responses. For spitzoid melanoma diagnoses, 90% of pathologists recommended excision with ≥10 mm margin. Pathologists report less confidence in diagnosing these lesions compared with other melanocytic proliferations and are more likely to request second opinions and additional clinical information (all p < 0.05).

CONCLUSIONS

Spitzoid lesions are often not classified in any standardized way, evoke uncertainty in diagnosis by pathologists, and elicit variability in treatment recommendations.

Pediatric Melanoma and Atypical Melanocytic Neoplasms

Melanoma is uncommon in the pediatric age range, but is increasing in frequency and often presents with atypical features compared to the classic ABCDE criteria common to adult melanoma cases. Moreover, many melanocytic neoplasms in childhood pose diagnostic challenges to the pathologist, and sometimes cannot be unequivocally classified as benign nevi or melanoma. This chapter addresses the evaluation and management of pediatric patients with melanoma and atypical melanocytic neoplasms, including the roles of and unresolved questions surrounding sentinel lymph node biopsy, completion lymphadenectomy, adjuvant therapy, and treatment of advanced disease.

Plexiform spitz nevus

In 1999, Spatz et al. reported the first 2 cases of a plexiform variant Spitz nevus. We describe another case of this variant on the upper thigh of a 10-year-old boy and discuss the differential diagnosis. Histologically, it comprised nodules of epithelioid cells with a plexiform arrangement distributed throughout the superficial and deep dermis. The cells had moderate eosinophilic cytoplasm with vesicular nuclei and prominent nucleoli. Intranuclear inclusions were present focally. The tumor nodules were embedded in a myxoid stroma with intratumoral and peritumoral inflammatory cells including both lymphocytes and eosinophils. There were occasional melanin-containing spindle-shaped cells. An intraepidermal component could not be assessed, since the lesion was ulcerated. The differential diagnosis includes both melanocytic and nonmelanocytic lesions exhibiting a plexiform pattern of growth as well as myxoid lesions.

Minimal deviation and/or naevoid melanoma: is recognition worthwhile? A clinicopathological study of nine cases

One to two per cent of primary cutaneous melanomas share clinical features with benign melanocytic and non-melanocytic skin lesions, and even at histology recognition of their malignant nature is problematic, mainly due to the lack of an intraepithelial component, their nodular aspect and the monotonous cell population throughout the lesion. These tumours were termed minimal deviation melanomas (MDMs) by Reed et al. and later naevoid melanomas by Schmoeckel et al. The name MDM suggests the concept of a more favourable outcome for these melanomas that do not (yet) show the typical features of fully evolved lesions able to metastasize, although naevoid melanomas seem to behave like 'common' melanomas. In a retrospective analysis of nine cases of MDM collected from our database and followed for a median duration of 112 months, we faced similar clinical and histological pitfalls and observed local recurrence following marginal resection. Wide excision, even of local recurrence, and therapeutic node dissection could nevertheless provide survival comparable at least to that predicted by mathematical models for patients who initially had optimal treatment.

Malignant melanoma, dysplastic melanocytic nevi, and Spitz tumors. Histologic classification and characteristics

The classification and pertinent histopathologic features of cutaneous melanoma, dysplastic melanocytic nevi, and Spitz tumors are presented. A discussion on melanoma emphasizes an objective approach to classification based on histomorphologic features including location in the skin, disposition and frequency of melanocytes, other specific morphologic features, and cell type. Other topics addressed include common and unusual variants of melanoma, the use of immunohistochemistry, and the histopathologic reporting of melanoma.

Hyalinizing spindle and epithelioid cell nevus. A study of five cases of a distinctive histologic variant of Spitz's nevus

Five cases are described of a distinctive histologic variant of benign spindle and epithelioid cell nevus characterized by extensive and prominent stromal hyalinization. The lesions consisted of a proliferation of spindle or epithelioid nevocytes scattered singly or in small clusters in the dermis and surrounded by abundant paucicellular hyalinized or collagenous stroma. Three patients were men and two were women. Their age range was 23 to 45 years (mean, 32). Two of the lesions were located in the head and neck region, two in the lower extremities, and one in the trunk. Immunohistochemical strains showed positive staining of the spindle or epithelioid cells with S-100 protein and vimentin; stains for keratin, EMA, CEA, actin, and desmin were all negative. Van Gieson and trichrome histochemical reaction demonstrated the collagenous nature of the hyalinized intercellular matrix; Congo red, crystal violet, and alcian blue stains were all negative. The etiology and pathogenesis of the intercellular hyalin deposits are unknown, but they probably represent a regressive phenomenon in longstanding or involuting lesions. Hyalinizing Spitz nevus must be included in the differential diagnosis of cutaneous lesions exhibiting a prominent hyalinized stroma and must be differentiated from other dermal neoplasms, particularly cutaneous metastases from occult internal malignancies and malignant melanoma.

Spindle and epithelioid cell nevus (Spitz nevus). Observation on nine cases

Nine cases with spindle and epithelioid cell nevus occurred in children were analysed clinically and morphologically. The results indicate that Spitz nevus is composed of cells resembling those of a malignant melanoma. There are some morphological aspects such as: discontinuous junctional proliferation, the sparse mitotic activity, the process of maturation of the cells with increasing depth, considered as valuable markers for the benign character of this type of tumour.