Spindle Cell Melanoma: A Comparison of the Cytomorphological Features with the Epithelioid Variant

Abstract

Objectives: Fine-needle aspiration cytology serves as a rapid and cost-effective tool for the diagnosis of melanoma, especially in the recurrent and metastatic cases. The diagnosis poses a challenge due to the varied morphological patterns. Spindle cell melanoma mimics other sarcomas and carcinomas on morphology. This study highlights the cytomorphological features of spindle cell melanoma and compares them with the conventional epithelioid type. Study Design: Cytology smears of 55 aspirates from 45 diagnosed cases of melanoma from various sites were reviewed. Histopathology correlation was done in spindle and mixed cell tumors. Results: Melanomas with a pure or mixed spindle cell component occurred in 31% of the cases and in a slightly higher age group. These demonstrated prominent cellular cohesion (p < 0.0001), mild to moderate nuclear atypia and inconspicuous to small nucleoli as compared to the epithelioid variant. The presence of melanin pigment was a useful clue to the diagnosis. Most of the cases correlated well with the histomorphology. Conclusion: Spindle cell melanoma is a morphological variant which can be readily misinterpreted due to a lack of classical cytological features of melanoma. Hence, these are vulnerable to be misinterpreted as other neoplasms. An awareness of clinical and cytological features is important to reach the correct diagnosis.

Metastatic spindle cell melanoma on cytology – a diagnostic challenge

“…The immunohistochemical markers used to confirm a melanocytic nature include S-100, HMB-45, Melan-A, and MART-1, the latter 3 being relatively specific but less sensitive markers for melanomas. Loss of expression of these makers has also been noted in spindle cell melanomas and few of them aberrantly express cytokeratin(10%) and smooth muscle actin [2,3,8]. In the present case HMB-45 was positive in the tumor cells.…”

“…There are two distinct subtypes of malignant melanoma that differ clinic-pathologically and with respect to prognostic features. These include the spindle cell variant and desmoplastic melanoma [2,3,11]. Both these tumors show atypical, spindle malignant melanocytes.…”

“…Spindle cell melanoma can occur anywhere on the body. Typically, it often presents with widespread metastatic disease [2,3]. However some melanomas may present as a metastasis of unknown primary origin while others may take several decades to develop metastasis [4].…”

<b><i>BRAF</i></b> V600 Mutational Status in Melanoma Correlates with Cytologic Features in Fine-Needle Aspirate Specimens

“…The presence of nuclear pseudoinclusions has been described as useful in the cytological differential diagnosis of melanoma [24]. Spindle cell morphology is not typical of melanomas and can represent a pitfall in cytological diagnosis [25]. However, the quantification of each of these morphologic features has not been reported before.…”

Metastatic leiomyosarcoma to the pancreas diagnosed on endoscopic ultrasound‐guided fine needle aspiration – A report of two cases with review of spindle cell lesions of pancreas

“…Spindle cell melanoma of the pancreas is very rarely reported in literature. According to Walia et al, spindle cell melanoma lacks classical cytological features (macronucleoli and cellular dyscohesion), leading to a misdiagnosis. A case of spindle cell melanoma of the heart from our institute displayed a peculiar cherry red nucleus in spindle cells, which was a diagnostic clue for applying ICC markers on cell‐block.…”