Cutaneous Mastocytosis With Atypical Mast Cells in a 7-Year-Old Girl

Abstract

Cutaneous mastocytosis is defined by the presence of mast cells within the skin in the absence of other criteria for the diagnosis of systemic mastocytosis. Mast cells are characterized by an abundant granular cytoplasm and a round to oval or spindle-shaped nuclei. The presence of mast cells with bilobed and multilobed nuclei in cutaneous mastocytosis is a rare phenomenon and has been rarely reported in the literature. To our knowledge, there are only 4 reported cases of cutaneous mastocytosis with atypical mast cells. We hereby report a case of urticaria pigmentosa in a 7-year-old female patient. The patient presented with asymptomatic skin lesions of several years duration over the neck and left scapular area. Histopathological examination revealed the presence of middermal perivascular infiltrates mainly composed of mast cells, few lymphocytes, and eosinophils. Most mast cells showed pleomorphic nuclei with bilobed and multilobed morphology that revealed a positive expression for CD117, tryptase, CD68, and Giemsa stains. Based on these findings the diagnosis of urticaria pigmentosa with atypical mast cells was made. Additional tests to rule out systemic involvement were performed. All values, including a tryptase level, were within normal limits. No changes were noted after 1-year follow-up.

Pleomorphic mastocytoma associated with loss of chromosome 5, PDGFRA, and HRAS mutations: A case of cutaneous mastocytosis with severe atypia and indolent behavior

“…2,5,6 Two cases described the presence of lesions for several years, 2,5 and one patient had a previous history of urticaria pigmentosa. 3 The most common location of PM was in the head and neck, 2,4,5 followed by the upper trunk 2,6 and upper extremity. 3 However, the authors did not identify HRAS, KRAS, or MRAS mutations in their KIT-D816V population.…”

“…Pleomorphic mastocytoma (PM) has been described as an unusual variant of CM displaying cytologic atypia without aggressive behavior or systemic involvement. [2][3][4][5][6] To the best of our knowledge, there are no reports of PM with loss of chromosome 5 and PDGFRA and HRAS mutations.…”

Case report of a clinically indolent but morphologically high‐grade cutaneous mast cell tumor in an adult: Atypical cutaneous mastocytoma or mast cell sarcoma?

“… 4 , 5 , 7 , 10 , 11 , 13 , 14 , 15 The recurrence in our case may be explained by small foci of mast cells in the resection margins. Although the WHO classification 1 states that atypia should be absent in mastocytoma, several case reports 7 , 17 , 18 , 19 , 20 , 21 showed that type II atypia of mast cells can occur in mast cell tumors with benign behavior. The nuclear pleomorphism in our case seemed to be more pronounced than described in the previous case reports.…”

“…1,16 A third type of cytomorphology consists of mast cells with nuclear pleomorphism, including bilobation and/or multilobation; these cells are known as atypical mast cell type II or promastocytes. 16 In the literature, nine cases of benign mastocytosis or mastocytoma of the skin with type II atypia have been reported, 7,[17][18][19][20][21] including two adult cases. 7,17 Although histomorphology raised concern about a malignant behavior, none of these patients showed systemic involvement or destructive growth, and after excision no recurrence was observed.…”

“…In the literature, nine cases of benign mastocytosis or mastocytoma of the skin with type II atypia have been reported, 7 , 17 , 18 , 19 , 20 , 21 including two adult cases. 7 , 17 Although histomorphology raised concern about a malignant behavior, none of these patients showed systemic involvement or destructive growth, and after excision no recurrence was observed.…”