Rare and Aggressive Primary Amelanotic Melanoma in Anorectal Region: A Case Series
ER01-ER05
Correspondence
Dr. V Archana,
Associate Professor, Department of Pathology, Dhanlakshmi Srinivasan Medical College and Hospital, Siruvachur, Perambalur-621113, Tamil Nadu, India.
E-mail: archanasureshraj@gmail.com
Anorectal amelanotic melanoma is a rare and aggressive disease with high morbidity and mortality. A conclusive diagnosis of anorectal amelanotic melanoma poses a challenge to pathologists and clinicians due to the protean nature of this entity, be it in its initial clinical assessment appearing as non pigmented polypoidal growths usually mistaken for haemorrhoids or anorectal polyps. Histomorphologically, these entities get categorised in bewildering array of diagnoses like spindle cell carcinoma, Gastrointestinal Stromal Tumour (GIST), High-grade sarcomas and even lymphoma. Thus, Immunohistochemistry (IHC) remains a vital tool for conclusive diagnosis. The purpose of the present case series is to discuss in detail about the three patients all aged above 55 years and clinically assessed with anorectal polypoidal growths. All three cases on histopathological evaluation were diagnosed as spindle cell neoplasm with no discernible melanin pigments. The IHC performed on all three cases turned positive for S-100 and Human Melanoma Black 45 (HMB45). The present case series highlights the challenging and bewildering nature of presentation of anorectal amelanotic melanomas, by virtue of its rarity and hence, justifies the need for it to be considered as a possible differential diagnosis.