Dermatologists diagnose and treat various skin disorders, including eczema, psoriasis, infections, and skin cancers. The average dermatologist sees 40 to 50 cases per day and is exposed to uncommon conditions, such as atypical Spitz tumors.

Considered borderline lesions, atypical Spitz tumors can make it challenging to predict metastatic risk or biologic behavior. Because they can resemble malignant melanoma, it is essential to recognize atypical Spitzoid tumors, become familiar with associated diagnostic testing, and partner with dermatopathology experts that can provide your patients with accurate and efficient results. 

Understanding Atypical Spitzoid Tumors

Lesions designated as atypical Spitzoid tumors (AST) confusingly appear as both Spitzoid melanomas and wholly benign Spitz nevi. Most commonly found in females with an average age of 22 years, the enigmatic lesion lacks standardized histological benchmarks, making consensus difficult for pathologists. 

Because of the difficulty in defining the biologic potential using morphology alone, dermatopathologists will sometimes order additional ancillary testing to help characterize the lesion. 

Additional testing platforms

Two techniques sometimes utilized to help characterize atypical Spitz tumors include Flourescence in-situ hybridization (FISH) and Array-based comparative genomic hybridization (aCGH). Flourescence in-situ hybridization (FISH) tests for characteristic chromosomal changes seen in tumors. Using a fluorescence microscope, short DNA fragments known as “FISH probes” are examined as they hybridize to tumor cells. By counting the resulting fluorescent dots, dermatopathologists can detect a loss or duplication of chromosome fragments. The method, used in combinations of four and five-probe FISH assays, is sometimes preferred as the primary molecular test because it is quick and straightforward and allows histopathologic correlation. In atypical Spitz tumors, probes are performed for covering the chromosomal loci 6p25, 8q24, 11q13, centromere 9, and 9p21.

Array-based comparative genomic hybridization (aCGH) is used to establish areas of genomic imbalance. While few academic centers perform CGH due to the high cost and limited insurance reimbursement, the method produces higher resolution results, which enable the identification of genes related to Spitzoid melanocytic neoplasms. When a Spitzoid neoplasm has a genetic pattern similar to malignant melanoma, this can potentially result in a poorer prognosis and possibly a reclassification to Spitzoid melanoma.

There are additional ancillary testing modalities marketed in the dermatology community to aid in the diagnosis of melanoma. None of these tests, however, have been shown to be consistently reliable; therefore, many dermatopathologists do not utilize them except in very rare circumstances.

Finding Experts in Molecular Testing 

When a dermatology clinic encounters an unfamiliar lesion, they turn to their dermatopathology laboratory for a correct and timely diagnosis. Aligning with a lab that embraces digital pathology can decrease turnaround time by 20 percent to up to 75 percent

Partnering with expert dermatopathologists, like the team at PathologyWatch, means access to academic-level interpretations and judicious use of ancillary tests when indicated. In addition, utilizing a digital pathology workflow enables simultaneous corroborations on difficult lesions by multiple experts. Having a team of qualified pathologists on your side can be the difference between diagnosing a tissue sample as Spitz nevus or Spitzoid melanoma. 

Though uncommon, your dermatology clinic may come across borderline lesions from time to time. By learning more about atypical Spitz tumors, understanding diagnostic testing, and knowing what to look for in a dermatopathology lab partner, you can empower your practice and continue to provide your patients with optimal care.