Histiocytoid Sweet Syndrome Is More Frequently Associated With Myelodysplastic Syndromes Than the Classical Neutrophilic Variant

Abstract

Histiocytoid Sweet syndrome (H-SS) is a histological variant of Sweet syndrome (SS) differing from classical neutrophilic SS (N-SS) by a dermal infiltrate mainly composed of lymphocytes and histiocytoid myeloperoxidase-positive cells. We aimed to report a large series of H-SS and compare the frequency and type of hematological malignancies associated to H-SS and N-SS. We included 62 patients with a coding histopathologic diagnosis of SS prospectively registered between 2005 and 2014 in the database of our Department of Pathology. Overall, 22 (35.5%) and 40 (64.5%) patients had a histological diagnosis of H-SS and N-SS, respectively. Median age, sex ratio, and cutaneous lesions were similar in the 2 groups. The frequency of extra-cutaneous manifestations was similar (50% vs 37.5%, P = 0.42). Recurrent forms were significantly more frequent in H-SS than in N-SS patients (21% vs 2.5%, P = 0.01). A hematological malignancy was diagnosed in 22 patients, 12 (55.5%) with H-SS and 10 (25%) with N-SS (P = .019). Hematological malignancy was of myeloid origin in 8/22 (36.3%) H-SS and 5/40 (12.5%) N-SS patients (P = .02), and of lymphoid origin without myeloid component in 4/22 (18.1%) H-SS and 4/40 (10%) N-SS patients (P = .35), respectively. One N-SS patient had a hematological malignancy of mixed (myeloid and lymphoid) phenotype. A myelodysplastic syndrome (MDS) was diagnosed in 7/22 (31.8%) H-SS and 1/40 (2.5%) N-SS patients (P < .001). Hematological disease was diagnosed before (in 8 H-SS and 3 N-SS patients) or at the time of the occurrence of the cutaneous lesions (in 1 H-SS and 7 N-SS patients). However, in 3 H-SS patients, all with MDS, cutaneous lesions preceded the hematological disease by ≤6 months. In conclusion, H-SS was associated with MDS in one third of patients but also with lymphoid malignancies, and cutaneous lesions could precede the hematological diagnosis in patients with MDS. A complete hematological assessment is mandatory at diagnosis, and monitoring blood cell counts should be recommended for at least 6 months after the diagnosis of H-SS.

Lymphocytes in Sweet syndrome: A potential diagnostic pitfall

“…There have also been several histologic variations reported in the literature. Jordaan reported variations in the cellular infiltrate, including lymphocytes, and years later, lymphocyte‐rich and histiocytoid lesions of SS were linked with myelodysplastic syndrome (MDS) . Similar to Jordaan's report, we have observed a consistent presence of lymphocytes in lesions of SS, in patients who do not have associated hematologic disorders.…”

Histiocytoid Sweet syndrome harboring an isocitrate dehydrogenase 1 mutation: A case report and retrospective analysis of 29 cases of histiocytoid Sweet syndrome

“…Our case demonstrates the importance of performing a complete blood count (CBC) at the time of diagnosis of HSS followed by thorough hematological evaluation should a cytopenia be detected. This case also supports a role for continued CBC monitoring in HSS as often, cutaneous HSS lesions may precede the diagnosis of hematologic malignancy …”

“…They concluded that the incidence of hematologic malignancies in HSS cases is comparable to that among classical SS cases, which is estimated at 18% . Other studies have described a possible unique association between HSS and MDS, with one case series reporting MDS in 5/13 (38%) HSS cases and another reporting MDS in 7/22 (31.8%) HSS cases . Fluorescence in situ hybridization (FISH) has been used to identify cytogenetic abnormalities occurring in cases of HSS associated with AML/MDS …”

Insights Into the Characteristics of Sweet Syndrome in Patients With and Without Hematologic Malignancy

“…A recent retrospective study showed the histiocytoid or subcutaneous variants exclusively in the setting of malignancy (14). Several studies have also suggested the relationship of histiocytoid or subcutaneous Sweet syndrome with hematologic disorders (16)(17)(18)(19). However, our cases did not show statistically significant differences in histopathology between the patients with and without hematologic malignancy.…”