Cutaneous Sarcoidal Granulomas

thinking outside of the box

57 year-old woman with a one-year history of an eruption on arms and legs

This 57 y.o. woman first noticed asymptomatic, erythematous patches on arms and legs a year ago.  She is in otherwise good health and was taking Losartan/ HCTZ and Pravastatin for hypertension and cholesterol by mouth.  She lived in Texas for five years in the 1980s, but otherwise spent her entire life in Western Massachusetts.

In September 2016, biopsies obtained from the right arm and left leg showed sarcoidal granulomatous dermatitis.

Clinical:
Her skin lesions, mostly on the arms and legs, are few and scattered. They are erythematous, slightly scaly, ill-defined plaques with irregular borders.

Pathology:
Photomicrographs graphs and interpretations courtesy of Dr. Deon Wolpowitz
Boston University, Department of Dermatology
The specimen exhibits superficial and deep, nodular well-formed collections of epithelioid histiocytes and multinucleated giant cells forming granulomas with sparse to mild lymphocytic rims and a moderate superficial and mid perivascular lymphocytic infiltrate. The histologic differential diagnosis includes sarcoidosis, a foreign body reaction, and infectious etiologies including mycobacterial infections. Polariscopic examination is negative. Fite stain is negative for mycobacteria. PAS stain is negative for fungal organisms.

Lab:  CBC and chemistries were normal, as was her chest x-ray.

Discussion:  This woman has no risk factors for sarcoidosis, but did spend five years in a geographic setting where sarcoid is more commonly seen. The only thing we came up with was that she was using a cat litter with silica in it and there is one reference in the literature to that being associated with sarcoidosis.

References:

1. Cat litter is a possible trigger for sarcoidosis.

Drent M, Wijnen PA, Boots AW, Bast A. Eur Respir J. 2012 Jan;39(1):221-2.  Free Full Text.  This is the fascinating report of a single case of pulmonary  sarcoidosis that appeared to be causally related to silica containing kitty litter.

2. Mahony J, Helms SE, Brodell RT.  The sarcoidal granuloma: A unifying hypothesis for an enigmatic response. Clin Dermatol. 2014 Sep-Oct; 32(5):654-9

Abstract: Although the cause of sarcoidosis is unknown, there is growing support for the concept that sarcoidal granulomas result from a hypersensitivity reaction producing a nonspecific response to an extrinsic or intrinsic (autoimmune) antigen in genetically susceptible individuals. The immune milieu associated with these antigens, localized in a specific cutaneous area, produces a variant of Ruocco's "immunocompromised district." This may explain the predilection for sarcoidal granulomas in association with foreign bodies, tattoos, herpes zoster-affected dermatomes, and scars. Similar antigenic stimulation produces sarcoidal granulomas surrounding internal tumors. Finally, systemic sarcoidosis, as manifested by hilar adenopathy, may reflect the lymphatic spread of foreign antigens.