Rare Variant of Melanoma: Clinical, Histopathological and Prognostic Features in 5 Cases of Animal Type Melanoma

OBJECTIVE: Animal type melanoma is a rare variant of melanoma. Our aim was to report clinical, histopathological and prognostic features in our series with 5 cases of animal type melanoma.
METHODS: Five cases with aminal type melanoma were included in the study. As clinical parameters age, gender, location of the lesion, lymph node involvement (sentinel or regional), duration of follow-up, development of satellite/in-transit/distant metastasis, and clinical stage were evaluated. As histopathological parameters cell type, Breslow thickness, Clark level, mitotic index, presence of ulceration, regression (partial/complete), lymphohistiocytic infiltration (absent/brisk/nonbrisk), and lymphovascular/perineural invasion were evaluated.
RESULTS: Mean age of the patients was 61 ± 17 (39-79) and female/male ratio was 3/2. Three lesions (60%) were located on head and neck region and remaining 2 (40%) were located on acral region. Median lesion size was 2,5 cm (1,5-4 cm) and Breslow thickness was 7,5 mm (4-19 mm). All lesions had Clark level V. Cell types were epitheloid in 3 lesions (60%), spindle in 1 lesion (20%) and epitheloid and spindle in 1 lesion (20%). Ulceration, lymphovascular and perineural invasion was present in 3 (60%), 2 lesions (40%) and 1 lesion (20%) respectively. Lymphohistiocytic infiltration was present in 3 lesions (60%) (nonbrisk in 2 lesions, brisk in 1 lesion). Regression (partial) was observed in 1 lesion (20%). Mitotic index was ≥ 1 mm–2 in 3 lesions (60%). Regional lymph node metastasis was present in 2 (%40) cases and distant metastasis developed in 2 (%40) cases.
CONCLUSION: In our series, animal type melanoma was observed between 4th-8th decades and both in females and males on head/neck or acral regions. In recent studies animal type melanoma has been reported to have a higher propensity to regional node metastasis but lower risk of distant metastasis compared to conventional melanoma. Similarly, lymph node involvement was high in our report, however distant metastasis rate was also high. In conclusion, further research is required about true biological potential of animal type melanoma.

Nadir Bir Melanom Varyantý: Hayvan Tipi Melanoma Sahip 5 Olguda Klinik, Histopatolojik ve Prognostik Özellikler

AMAÇ: Hayvan tipi melanom, melanomun nadir bir varyantýdýr. Çalýþmamýzda 5 olguluk serimize ait klinik, histopatolojik ve prognostik özelliklerin sunulmasý amaçlanmýþtýr.
YÖNTEMLER: Hayvan tipi melanoma sahip 5 olgu çalýþmaya dahil edildi. Klinik parametreler olarak yaþ, cinsiyet, lokalizasyon, boyut, lenf nodu (sentinel/bölgesel) tutulumu, takip süresi ve satellit/intransit/uzak metastaz geliþimi ve klinik evre deðerlendirildi. Histopatolojik olarak hücre tipi, Breslow kalýnlýðý, Clark seviyesi, mitotik indeks, ülserasyon, regresyon (parsiyel/tam), lenfohistiyositik infiltrasyon (yok/hafif/yoðun) ve lenfovasküler/perinöral invazyon varlýðý deðerlendirildi.
BULGULAR: Hastalarýn ortalama yaþý 61 ± 17 (39-79) ve kadýn/erkek oraný 3/2 idi. Lezyonlarýn 3’ü (%60) baþ-boyun, 2’si (%40) akral yerleþimli idi. Ortanca boyut 2.5 cm (1.5-4 cm) ve Breslow kalýnlýðý 7.5 mm (4-19 mm) idi. Tüm lezyonlarýn Clark seviyesi V idi. Hücre tipi, 3 lezyonda (%60) epiteloid, 1 lezyonda (%20) iðsi ve 1 lezyonda (%20) epiteloid ve iðsi karakterde idi. Üç lezyonda (%60) ülserasyon, 2 lezyonda (%40) lenfovasküler ve 1 lezyonda (%20) perinöral invazyon mevcuttu. Üç lezyonda (%60) lenfohistiyositik infiltrat (2 lezyonda hafif ve 1 lezyonda yoðun) ve 1 lezyonda (%20) regresyon (parsiyel) izlendi. Üç lezyonda (%60) mitotik indeks ≥ 1 mm–2 idi. Ýki olguda (%40) bölgesel lenf nodunda metastaz mevcuttu. Ýki olguda (%40) uzak metastaz geliþmiþti.
SONUÇ: Serimizde hayvan tipi melanomlar 4-8. dekadlar arasýnda, hem kadýn hem de erkeklerde izlendi. Baþ-boyun veya akral bölge yerleþimli idi. Son yayýnlarda hayvan tipi melanomda lenf nodu tutulumunun yüksek ve uzak metastaz geliþiminin klasik melanoma kýyasla daha düþük olduðundan bahsedilmektedir. Bizim serimizde de lenf nodu tutulumu yüksekti, fakat bundan farklý olarak uzak metastaz oraný da yüksekti. Sonuç olarak bu nadir melanom variyantýnýn gerçek biyolojik potansiyeli hakkýnda daha ileri çalýþmalara ihtiyaç vardýr.