B. Dmitrović i suradnici: Desmoplastic malignant melanoma. Med Vjesn 1991; 23( 1-2) 45-49 45 Desmoplastic malignant melanoma Case report, immunohistochemical observations and review of literature Branko Dmitrović and Ante Trošić Stručni rad U D K 616-006.8-08 Received: 3 rd January, 1991 Department of Pathology, General Hospital Osijek A case of malignant melanoma with a desmoplastic recurrence and local lymph node metastasis is repor- ted. The local relapse and the axillary metastasis presented the desmoplastic variant without atypical melanocytes that were easily recognised in primary lesion. Histological slices were examined by light microscopy and iminunohistochemically. Melanin could not be demonstrated in either recur- rence or metastasis by histochemical tehnique. Im- munoperoxidase staining with anti S-100 protein an- tibody demonstrated diffuse positivity of spindle cells both in relapse and metastasis, allowing the assesment of the depth of invasion. All the sections were negative for vimentin, desmin and neuron-spe- cific enolase. Key words: desmoplastic malignant melanoma, immunohistochemistry Malignant melanoma may assume various histologi- cal and clinical patterns. One of them is known as desmoplastic malignant melanoma (DMM), first reco- gnised in 1971 (1). Melanomas with this histological pattern can be easily confused with a large number of other spindle-cell reactions and neoplasms. DMM shows a distinct propensity toward repeated local recurrence but may also give rise to systemic metastases and death. In this report, a case of DMM and the immunostain properties of the DMM tissue are described. CASE REPORT A 62-year-old woman noticed that a mole on her left forearm had enlarged together with the nodule beneath the initial lesion. The excision was performed in April 1986. A pigmented lesion 6 mm in diameter overlying the grayish-white nodule of fibrous appearance was noted. The centre of the pigmented lesion was ulcerated. Near the edges of ulceration, small groups of atypical melanocytes were observed both in epidermis and in the junctional zone. Toward the depth of the lesion, there was a slight transition between atypical melanocytes of spindle or epitheloid appearance and fibroblast-like cells with abundant collagen stroma performing the storiform pattern. The lesion was not sharply demarca- ted from the subcutaneous fat tissue. It was diagnosed as malignant melanoma (figure 1). In July 1987 the same patient was readmitted to hospital because of a hard nodule arising at the site of previous excision. Wide excision was performed once again, revealing a grayish nodule 25 mm in diameter, infiltrating subcutaneous tissue extensively. A diagno- sis of DMM was made on review of the previous biopsy (figure 2). In October 1987 the patient palpated a hard nodule in her left axilla, and a smaller one on the site of the two earlier biopsies. Histological examination of a small nodule 4 mm in diameter revealed granulomatous in- flamation with the multinucleated cells of the foreign- -body type around the surgical material, with no tu- mour regrowth. However, axillary biopsy of a hard infiltrating grayish nodule 53 mm in diameter was diagnosed as a metastasis of the DMM. Histological appearance of the axillary lesion was that of the recur- rence, with long spindle cells occasionally having enlar- ged hyperchromatic nuclei, with no melanin content, in a background of proliferating connective tissue with abundant collagen (figure 3). After a year, the patient was lost to follow-up.