Joint Decisions

Histiocytoid Sweet Syndrome

At first glance, it appeared that a straightforward diagnosis was in order, said Dr. Paul A. Krusinski at the annual meeting of the Noah Worcester Dermatological Society.

“We thought it looked pretty good for Sweet syndrome,” he said, referencing the patient's characteristic fever and joint pain. “Often, Sweet syndrome has a prodrome associated with it and she had her—quote—sinus infection,” he said.

A second differential diagnosis was drug hypersensitivity reaction, noted Dr. Krusinski, professor and director of the division of dermatology at the University of Vermont, Burlington.

Histologically, edema could be seen in the upper papillary dermis. A perivascular infiltrate was evident in the dermis. At higher power, however, the Sweet syndrome diagnosis seemed less likely. “When you get a little closer, you say, 'Where are the polys [polymorphonuclear neutrophils]? Where are the neutrophils?'” he said. In their place appeared to be large histiocytes.

A dermatopathology report on an initial biopsy specimen identified “a moderately dense dermal inflammatory infiltrate that is of mixed composition but predominated by mononuclear cells,” and went on to note that “only rare neutrophils are present, thus militating against Sweet syndrome.” Immunostaining was positive for CD68 and myeloid precursors.

Classic Sweet syndrome, first described in 1964, is characterized by its female predominance, abrupt onset, fever, painful erythematous plaques or nodules, and abnormal laboratory values such as elevated erythrocyte sedimentation rate and positive C-reactive protein, just as in this case.

Neutrophilic infiltrate conventionally heralds classic Sweet syndrome, either in the absence of vasculitis or, rarely, with secondary vasculitis. Three subtypes are classically described, including idiopathic Sweet syndrome associated with other inflammatory diseases, cases related to hematologic malignancies, and cases associated with solid malignant neoplasms.

A literature review revealed a study from Spanish researchers detailing 41 cases of a previously undescribed entity: histiocytoid Sweet syndrome. In this series, 26 women and 15 men aged 29–79 years had lesions typical of Sweet syndrome but failed to meet conventional histopathologic criteria for the disease (Arch. Dermatol. 2005;141:834–42).

Biopsies showed dense, bandlike infiltrate in the superficial dermis and mid-dermis that was predominated by large mononuclear cells with “eccentric” nuclei and irregular contours. Few neutrophils, lymphocytes, or small histiocytes were present. Moderate to intense superficial dermal edema was present and there was no appreciable vasculitis.

Findings align with the monocytic histiocytic lineage, with positive staining for CD15, CD43, CD45, CD68, MAC-386, HAM56, and lysozyme.

The authors of a recent article detailing six clinically and microscopically diverse cases thought to be Sweet syndrome, drug eruptions, erythema nodosum, or Wells's syndrome hypothesized that histiocytoid neutrophilic dermatoses and panniculitides are “variations on a theme” and proposed three new disease classifications: Sweetlike neutrophilic dermatoses, histiocytoid; subcutaneous Sweet syndrome, histiocytoid; and histiocytoid neutrophilic dermatosis, unspecified (Am. J. Dermatopathol. 2007;29:334–41).

The case patient had age-appropriate cancer screening, with negative results, and responded well to prednisone 40 mg daily followed by a tapering of the drug.

Dr. Kathryn Schwarzenberger was the physician at the University of Vermont who made the diagnosis.

Histology shows dense dermal inflam-matory infiltrate of mononuclear cells. Courtesy Dr. Paul A. Krusinski

Histiocytoid Sweet Syndrome

At first glance, it appeared that a straightforward diagnosis was in order, said Dr. Paul A. Krusinski at the annual meeting of the Noah Worcester Dermatological Society.

“We thought it looked pretty good for Sweet syndrome,” he said, referencing the patient's characteristic fever and joint pain. “Often, Sweet syndrome has a prodrome associated with it and she had her—quote—sinus infection,” he said.

A second differential diagnosis was drug hypersensitivity reaction, noted Dr. Krusinski, professor and director of the division of dermatology at the University of Vermont, Burlington.

Histologically, edema could be seen in the upper papillary dermis. A perivascular infiltrate was evident in the dermis. At higher power, however, the Sweet syndrome diagnosis seemed less likely. “When you get a little closer, you say, 'Where are the polys [polymorphonuclear neutrophils]? Where are the neutrophils?'” he said. In their place appeared to be large histiocytes.

A dermatopathology report on an initial biopsy specimen identified “a moderately dense dermal inflammatory infiltrate that is of mixed composition but predominated by mononuclear cells,” and went on to note that “only rare neutrophils are present, thus militating against Sweet syndrome.” Immunostaining was positive for CD68 and myeloid precursors.

Classic Sweet syndrome, first described in 1964, is characterized by its female predominance, abrupt onset, fever, painful erythematous plaques or nodules, and abnormal laboratory values such as elevated erythrocyte sedimentation rate and positive C-reactive protein, just as in this case.

Neutrophilic infiltrate conventionally heralds classic Sweet syndrome, either in the absence of vasculitis or, rarely, with secondary vasculitis. Three subtypes are classically described, including idiopathic Sweet syndrome associated with other inflammatory diseases, cases related to hematologic malignancies, and cases associated with solid malignant neoplasms.

A literature review revealed a study from Spanish researchers detailing 41 cases of a previously undescribed entity: histiocytoid Sweet syndrome. In this series, 26 women and 15 men aged 29–79 years had lesions typical of Sweet syndrome but failed to meet conventional histopathologic criteria for the disease (Arch. Dermatol. 2005;141:834–42).

Biopsies showed dense, bandlike infiltrate in the superficial dermis and mid-dermis that was predominated by large mononuclear cells with “eccentric” nuclei and irregular contours. Few neutrophils, lymphocytes, or small histiocytes were present. Moderate to intense superficial dermal edema was present and there was no appreciable vasculitis.

Findings align with the monocytic histiocytic lineage, with positive staining for CD15, CD43, CD45, CD68, MAC-386, HAM56, and lysozyme.

The authors of a recent article detailing six clinically and microscopically diverse cases thought to be Sweet syndrome, drug eruptions, erythema nodosum, or Wells's syndrome hypothesized that histiocytoid neutrophilic dermatoses and panniculitides are “variations on a theme” and proposed three new disease classifications: Sweetlike neutrophilic dermatoses, histiocytoid; subcutaneous Sweet syndrome, histiocytoid; and histiocytoid neutrophilic dermatosis, unspecified (Am. J. Dermatopathol. 2007;29:334–41).

The case patient had age-appropriate cancer screening, with negative results, and responded well to prednisone 40 mg daily followed by a tapering of the drug.

Dr. Kathryn Schwarzenberger was the physician at the University of Vermont who made the diagnosis.

Histology shows dense dermal inflam-matory infiltrate of mononuclear cells. Courtesy Dr. Paul A. Krusinski

Histiocytoid Sweet Syndrome

At first glance, it appeared that a straightforward diagnosis was in order, said Dr. Paul A. Krusinski at the annual meeting of the Noah Worcester Dermatological Society.

“We thought it looked pretty good for Sweet syndrome,” he said, referencing the patient's characteristic fever and joint pain. “Often, Sweet syndrome has a prodrome associated with it and she had her—quote—sinus infection,” he said.

A second differential diagnosis was drug hypersensitivity reaction, noted Dr. Krusinski, professor and director of the division of dermatology at the University of Vermont, Burlington.

Histologically, edema could be seen in the upper papillary dermis. A perivascular infiltrate was evident in the dermis. At higher power, however, the Sweet syndrome diagnosis seemed less likely. “When you get a little closer, you say, 'Where are the polys [polymorphonuclear neutrophils]? Where are the neutrophils?'” he said. In their place appeared to be large histiocytes.

A dermatopathology report on an initial biopsy specimen identified “a moderately dense dermal inflammatory infiltrate that is of mixed composition but predominated by mononuclear cells,” and went on to note that “only rare neutrophils are present, thus militating against Sweet syndrome.” Immunostaining was positive for CD68 and myeloid precursors.

Classic Sweet syndrome, first described in 1964, is characterized by its female predominance, abrupt onset, fever, painful erythematous plaques or nodules, and abnormal laboratory values such as elevated erythrocyte sedimentation rate and positive C-reactive protein, just as in this case.

Neutrophilic infiltrate conventionally heralds classic Sweet syndrome, either in the absence of vasculitis or, rarely, with secondary vasculitis. Three subtypes are classically described, including idiopathic Sweet syndrome associated with other inflammatory diseases, cases related to hematologic malignancies, and cases associated with solid malignant neoplasms.

A literature review revealed a study from Spanish researchers detailing 41 cases of a previously undescribed entity: histiocytoid Sweet syndrome. In this series, 26 women and 15 men aged 29–79 years had lesions typical of Sweet syndrome but failed to meet conventional histopathologic criteria for the disease (Arch. Dermatol. 2005;141:834–42).

Biopsies showed dense, bandlike infiltrate in the superficial dermis and mid-dermis that was predominated by large mononuclear cells with “eccentric” nuclei and irregular contours. Few neutrophils, lymphocytes, or small histiocytes were present. Moderate to intense superficial dermal edema was present and there was no appreciable vasculitis.

Findings align with the monocytic histiocytic lineage, with positive staining for CD15, CD43, CD45, CD68, MAC-386, HAM56, and lysozyme.

The authors of a recent article detailing six clinically and microscopically diverse cases thought to be Sweet syndrome, drug eruptions, erythema nodosum, or Wells's syndrome hypothesized that histiocytoid neutrophilic dermatoses and panniculitides are “variations on a theme” and proposed three new disease classifications: Sweetlike neutrophilic dermatoses, histiocytoid; subcutaneous Sweet syndrome, histiocytoid; and histiocytoid neutrophilic dermatosis, unspecified (Am. J. Dermatopathol. 2007;29:334–41).

The case patient had age-appropriate cancer screening, with negative results, and responded well to prednisone 40 mg daily followed by a tapering of the drug.

Dr. Kathryn Schwarzenberger was the physician at the University of Vermont who made the diagnosis.

Histology shows dense dermal inflam-matory infiltrate of mononuclear cells. Courtesy Dr. Paul A. Krusinski