|Year : 2014 | Volume
| Issue : 1 | Page : 35-38
Metastatic malignant subungal melanoma: Importance of FNAC
Radhika Punshi Nandwani, Murali Gopala Krishnan, Sanjay Kumar Totade
Department of Pathology, Netaji Subhash Chandra Bose Medical College, Jabalpur, Madhya Pradesh, India
|Date of Web Publication||24-Jun-2014|
Radhika Punshi Nandwani
M 57, Sharda Society, Shakti Nagar, Jabalpur - 482 001, Madhya Pradesh
Source of Support: None, Conflict of Interest: None
Subungual melanoma is a rare type of skin cancer. It is an uncommon form of acral lentiginous melanoma. Approximately 85% of cases are misdiagnosed initially, and it is generally associated with a poor prognosis. Herein, we describe a case of metastatic subungal melanoma to the axillary lymph node in a 45-year-old male. Diagnosis of metastasis was made based on cytology, where the clinicians were guided to search for primary. This case report highlights the role of fine-needle aspiration cytology (FNAC) in the diagnosis of this entity to draw the attention of the reader to the possible underreporting of melanoma because of a variant that evades diagnosis and our reluctance to think about its existence.
Keywords: Fine-needle aspiration cytology, lymph node deposit, primary subungal melanoma
|How to cite this article:|
Nandwani RP, Krishnan MG, Totade SK. Metastatic malignant subungal melanoma: Importance of FNAC. Indian J Dermatopathol Diagn Dermatol 2014;1:35-8
|How to cite this URL:|
Nandwani RP, Krishnan MG, Totade SK. Metastatic malignant subungal melanoma: Importance of FNAC. Indian J Dermatopathol Diagn Dermatol [serial online] 2014 [cited 2019 Feb 17];1:35-8. Available from: http://www.ijdpdd.com/text.asp?2014/1/1/35/135196
| Introduction|| |
Malignant melanoma accounts for 1-3% of all malignancies with an increasing incidence being seen worldwide. Subungual malignant melanoma, a form of acral lentigious melanoma is a rare disease with reported incidence between 0.7-3.5% of all melanoma cases in the general population.  It accounts for 23% of melanomas in the Japanese population, 25% in the Afro-Caribbean population, and 1-3% in the White population. In one study on subungual melanomas, finger nails were affected in 62% and toe nails in 38%. The thumb and great toe nails were affected in 73%.  Other studies, also confirm the most common sites of involvement as the great toes, followed by thumb. Diagnosis is often delayed in those with subungual melanoma with patients going on to have a poorer prognosis than those with cutaneous melanoma and approximately 85% of cases are misdiagnosed initially. Estimated 5-year survival is between 16 and 87%.  Early detection of both primary malignant melanoma and metastatic disease is important for initiation of appropriate treatment. Fine-needle aspiration (FNA) represents a rapid, relatively inexpensive, and minimally invasive means to sample and diagnose metastases in patients with melanoma and potentially prevent more invasive procedures such as surgical excisions. This case presents the utility of FNA technique in diagnosis of metastatic melanoma in our setup.
| Case Report|| |
A 45-year-old man presented with large left-sided axillary lump, since 4 months, gradually increasing in size. With a clinical opinion of axillary lymphadenopathy and D/d (differential diagnosis) of 1. tuberculosis 2. lymphoma patient was referred to cytology section for FNAC.
On examination, a well-defined 7 × 5 cm, fixed, firm to hard mass in the left axilla was observed. The mass was aspirated with a 23-gauge needle and the specimen spread on a slide, fixed in alcohol and stained with hematoxylin and eosin (H and E) stain [Figure 1].
|Figure 1: Large, well-defined, 7 × 5 cm, non-mobile, and firm to hard lump involving anterior axillary fold on left side|
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FNAC of lymph node was performed. FNAC of the mass yielded blackish fluid. Cytological examination of the aspirate revealed hyper cellular smear with round to oval and spindle-shaped epithelial cells loosely arranged with pleomorphic, central, and eccentrically placed nuclei and prominent nucleoli, with abundant cytoplasm containing brownish pigment. A few pigment-laden macrophages were also seen. Few binucleated, multinucleated, and giant cells were seen [Figure 2]. A cytological diagnosis of metastatic deposits of malignant melanoma was given and search for primary was advised. Review of the patient's history was elicited.
|Figure 2: (a) Cytological features of aspirate admixture of epithelial and oval cells (H and E, ×40). (b) Dispersed malignant cells with marked nuclear pleomorphism and prominent nucleoli with abundant cytoplasm-containing brown pigment (×100). (c) Few tumor cells are binucleate and pigment-laden cell is also seen (×40). (d) Few tumor cells multinucleate. Some cells showing pigment in cytoplasm (H and E, ×100). H and E = Hematoxylin and eosin|
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Cutaneous examination revealed a non-tender, 2 × 1 cm, haphazard pigmentation on the left thumb [Figure 3] involving the nail bed, proximal thumb tip and pulp. The lesion showed macular pigmentation. There was a brown longitudinal band on the nail plate. Punch biopsy was advised.
|Figure 3: Cutaneous examination revealed a non-tender, 2 × 1 cm, and haphazard pigmentation on the left thumb involving the nail bed and proximal nail fold|
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Histopathological examination of lesion revealed proliferation of atypical melanocytic cells. Cells showed pleomorphic nuclei and melanin pigment. Mitotic figures averaged five per high-power field. The tumor cells invaded the dermis and reached the subcutaneous (Clarks level 5). Features were consistent with malignant melanoma [Figure 4]A. Histopathological examination of his axillary lymph node specimen revealed large pleomorphic tumor cells with pleomorphic nuclei and external pigment and increased mitotic activity, just below the capsule. Features were positive for metastatic melanoma [Figure 4]B. Immunohistochemistry (IHC) of biopsies that were sent to higher center showed positive result for HMB-45(IHC) and MELAN-A, thus confirming the diagnosis of malignant melanoma with metastasis of melanoma in lymph node.
Patient was referred to surgical oncology clinic. A computed tomography (CT) thorax showed metastatic lesion in cervical and hilar lymph nodes as well as in lung. The patient was referred for chemotherapy.
| Discussion|| |
Subungual malignant melanoma, a form of acral lentigious melanoma is a rare disease with reported incidence between 0.7-3.5% of all melanoma cases in the general population.  Studies have shown that the most common sites of involvement are the great toes, followed by thumb.  Diagnosis is often delayed in those with subungual melanoma with patients going on to have a poorer prognosis than those with cutaneous melanoma, and approximately 85% of cases are misdiagnosed initially.  The frequent delay in correct diagnosis of such lesions often results in frankly invasive tumors, sometimes with distant metastasis before they are correctly managed.
There are few reports in the literature on cutaneous malignant melanoma in the Asian population. Cancer registries in India report that the age-specific incidence rates for cutaneous malignant melanoma are less than 0.5 per 1,000,000.  The most common sites of involvement are the great toes, followed by thumb. Melanoma metastases generally occur in regional lymph nodes first, with or without later development of distant metastases (most often in skin, lungs, liver, central nervous system, and bone).  Metastases usually become apparent clinically or are detected during routine follow-up after treatment of the primary lesion. 
In our case, patient was unaware of the primary lesion and lymphatic spread had already occurred. FNAC was instrumental in directing the clinicians to the possible diagnosis.
The pathologic diagnosis of melanoma metastases can be achieved by FNAC or open biopsy. FNAC has proven to be a valuable tool for diagnosis of metastatic and primary melanoma. FNAC represents a highly effective method because on-site assessments for cellular adequacy allows verification of tumor cell acquisition and leads to significant savings in time and cost. FNAC has the advantages of rapidity, safety and noninvasiveness. It is a highly accurate and reliable technique that is well tolerated by patients when performed by properly trained operators. It allows rapid tissue diagnosis and is of great help in saving time and reducing costs and allows early treatment. 
In our case, morphologic features of aspirate were in favor of a metastasis of melanoma and malignancy was diagnosed for the first time by the FNAC. Our certainty of cytological diagnosis along with effective clinical history and examination helped us to reach accurate diagnosis. Histopathological examination along with IHC of the excised lesion was used as the reference standard. In the present case, FNAC played a major role in obtaining the accurate diagnosis with the help of clinical history and examination and facilitated institution of prompt treatment.
This report highlights the characteristics of subungal melanoma and emphasizes the importance of FNAC in diagnosing it. The primary knowledge of its existence and evaluation of its cytological features are important for a correct preoperative cytological diagnosis and thereby clinical implications for appropriate therapeutic intervention.
FNAC is a highly accurate, rapid, and cost-effective procedure for the diagnosis of metastatic melanoma and should be considered as the initial diagnostic procedure of choice in patients with melanoma with clinically suspected metastases. The cellular material obtained from FNAC can be used for diagnostically, prognostically, and therapeutically relevant ancillary studies. 
We conclude that clinicians should make judicious use of the simple and non-invasive/minimally invasive cytological techniques in the management of melanoma patients.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]