although traditionally malignant melanoma has been considered a tumor of the caucasians , recently , an increasing incidence is being noted in india .
we present here a case of malignant melanoma , resembling a vascular tumor ; the first of its kind from the indian subcontinent .
a 40-year - old gentleman presented to us with multiple asymptomatic , pigmented , nodular lesions , resembling cluster of grapes , distributed over the medial aspect of right lower limb .
initially , there was a single nodular lesion , which rapidly increased in size over the next 3 months ; gradually new nodules arose in the vicinity which coalesced with each other to form a plaque .
he also complained of heaviness due to a mass in his right groin . his past medical and surgical history including drug history were unremarkable
. fever or other constitutional symptoms were absent except for the presence of significant weight loss and occasional episodes of bleeding from the lesions when subjected to trivial trauma ; he also complained of occasional breathlessness and two episodes of bloody expectoration following cough . on dermatological examination ,
multiple dome - shaped nodular lesions were found on the distal part of right lower limb ; ranging from 2 - 3 mm in diameter to plaque of 5 cm  7 cm with bosselated surface ; formed by the coalescence of individual nodules [ figure 1 ] .
the color varied from light to dark mottled brown with some lesions showing atrophy and superficial ulceration .
on palpation , they were firm , nontender nodules with the smooth , glossy surface , with woody hard induration of the underlying skin .
general survey was normal except for the presence of pallor and a palpable mass in the right inguinal region sized about 7 cm  3 cm which was hard and immobile [ figure 2 ] .
routine hematologic and biochemical investigations were within normal limits except for the presence of anemia ( hb - 8.4g / dl ) and an elevated erythrocyte sedimentation rate ( 55 mm / h ) .
the patient was referred to the department of general medicine to evaluate his respiratory complaint and rule out any other evidence of systemic metastasis .
( a and b ) multiple brownish dome - shaped nodular lesions with a bosselated surface , right lower limb right inguinal lymphadenopathy on histopathological examination ( hpe ) , sections showed a proliferative growth centered in the upper dermis with marked thinning of the epidermis [ figure 3 ] .
tumor cells were arranged in nests with focal infiltration of adnexa [ figure 4 ] .
the cells were polygonal with hyperchromatic nuclei , perinuclear halo , and prominent nucleoli ; also inclusion bodies were found with conspicuous mitotic activity [ figure 5 ] .
proliferative growth in the upper dermis with marked thinning of epidermis ( h and e , 40 ) lobulated mass showing closely packed pigmented cells ( h and e , 100 ) the mass showing clustered polygonal cells with hyperchromatic nuclei and perinuclear halo ( h and e , 400 )
clark et al . divided malignant melanoma into three main subsets , by using a combination of clinical and pathological features ; the superficial spreading melanoma , the nodular melanoma , and the lentigo maligna melanoma .
the national institutes of health consensus conference on the diagnosis of melanoma has suggested the use of the asymmetry , border irregularity , color variegation , diameter > 6 mm checklist for the detection of melanocytic lesions .
risk factors for the development of melanoma may be divided into three categories : phenotypic manifestations of gene / environment interactions , environmental factor , and genetic factors .
the histological diagnosis of melanoma is based on the assessment of a constellation of findings , including both architectural and cytological features .
cytological atypia , nuclear enlargement , nuclear pleomorphism , hyperchromasia of nuclei , nucleolar variability , and the presence of mitoses especially deep in the dermis , is considered necessary for a diagnosis of melanoma .
there is a lack of maturation of nests of melanocytes with a descent into the dermis .
pagetoid spread of large solitary epidermal melanocytes is usually considered diagnostic of melanoma . in our case ,
kaposi sarcoma is multifocal , endothelial proliferation predominantly involving the skin and other organs and associated with the formation of vascular channels and proliferation of the spindle - shaped cell .
clinically , skin lesions vary from small violaceous papules to large plaques to ulcerated nodules .
initially , the upper body is involved , often along skin lines in a pityriasis rosea - like pattern and at sites of local trauma .
lesions develop on the face , in particular , the nose , and on oral mucosal surfaces , including the gums and hard palate . during tumor progression
the color changes to brownish and the skin overlying the tumor becomes hyperkeratotic and , in particular on the lower extremities , may ulcerate .
on hpe , tumor lobules are composed of bland , spindle - shaped cells with poorly defined , pink cytoplasm along with extensive vascular proliferation at all levels of the dermis .
retiform hemangioendothelioma presents mainly in young adults , with no sex predilection , as a slowly growing , asymptomatic , dermal , and subcutaneous plaque or nodule .
histology reveals arborizing , thin - walled , narrow , vascular channels with a striking resemblance to the rete testis .
dusky blue or red nodules develop and grow rapidly , and fresh , discrete nodules appear nearby . in some cases , hemorrhagic blisters are a prominent feature .
as the tumors grow , the edema may increase , and older lesions may ulcerate . on histology vascular channels
infiltrate the normal structures in a disorganized fashion along with the characteristic  dissection of collagen .  in our case , none of the histological features of hemangioendothelioma or angiosarcoma was present .
there have been reports of rare disseminated malignant melanoma presenting as multiple asymptomatic , nodular lesions on the trunk , extremities , and the face and a rare sporotrichoid pattern of malignant melanoma . however , our case is unique as it is malignant melanoma mimicking closely mimicking a vascular tumor ; where the final diagnosis could only be reached on hpe .
very few reports have depicted an unilateral distribution of malignant melanoma ; in our case also the lesions are unilateral ; distributed only over the right lower limb ; this has further added to the uniqueness of our case .
malignant melanoma is itself a rare disease in our set - up , further the unilateral distribution and clinical resemblance to vascular tumors has made our case even more unique ; all these features prompted the current case report .
there are no conflicts of interest . a rare report of malignant melanoma from the indian subcontinent region , which clinically resembled a vascular tumor ; histopathological examination clinched the final diagnosis
there are no conflicts of interest . a rare report of malignant melanoma from the indian subcontinent region , which clinically resembled a vascular tumor ; histopathological examination clinched the final diagnosis
 malignant melanoma is an invasive neoplasm of the skin , whose incidence is reported to be rising among indians . 
 we hereby present a unique case of unilateral , multiple , asymptomatic , pigmented , nodular lesions over the lower limb ; resembling vascular tumor , revealing itself as malignant melanoma only on histopathology . to the best of our knowledge 
 , such a unique presentation of malignant melanoma has not yet been reported from the indian subcontinent . 